U.S. patent number 8,450,543 [Application Number 12/986,918] was granted by the patent office on 2013-05-28 for integrated methods of preparing renewable chemicals.
This patent grant is currently assigned to Gevo, Inc.. The grantee listed for this patent is Josefa M. Griffith, Patrick R. Gruber, David E. Henton, Leo E. Manzer, Yassin Al Obaidi, Matthew W. Peters, Joshua D. Taylor. Invention is credited to Josefa M. Griffith, Patrick R. Gruber, David E. Henton, Leo E. Manzer, Yassin Al Obaidi, Matthew W. Peters, Joshua D. Taylor.
United States Patent |
8,450,543 |
Peters , et al. |
May 28, 2013 |
Integrated methods of preparing renewable chemicals
Abstract
Isobutene, isoprene, and butadiene are obtained from mixtures of
C.sub.4 and/or C.sub.5 olefins by dehydrogenation. The C.sub.4
and/or C.sub.5 olefins can be obtained by dehydration of C.sub.4
and C.sub.5 alcohols, for example, renewable C.sub.4 and C.sub.5
alcohols prepared from biomass by thermochemical or fermentation
processes. Isoprene or butadiene can be polymerized to form
polymers such as polyisoprene, polybutadiene, synthetic rubbers
such as butyl rubber, etc. in addition, butadiene can be converted
to monomers such as methyl methacrylate, adipic acid, adiponitrile,
1,4-butadiene, etc. which can then be polymerized to form nylons,
polyesters, polymethylmethacrylate etc.
Inventors: |
Peters; Matthew W. (Highlands
Ranch, CO), Taylor; Joshua D. (Evergreen, CO), Henton;
David E. (Midland, MI), Manzer; Leo E. (Wilmington,
DE), Gruber; Patrick R. (Longmont, CO), Griffith; Josefa
M. (Parker, CO), Obaidi; Yassin Al (Somerset, KY) |
Applicant: |
Name |
City |
State |
Country |
Type |
Peters; Matthew W.
Taylor; Joshua D.
Henton; David E.
Manzer; Leo E.
Gruber; Patrick R.
Griffith; Josefa M.
Obaidi; Yassin Al |
Highlands Ranch
Evergreen
Midland
Wilmington
Longmont
Parker
Somerset |
CO
CO
MI
DE
CO
CO
KY |
US
US
US
US
US
US
US |
|
|
Assignee: |
Gevo, Inc. (Englewood,
CO)
|
Family
ID: |
44259023 |
Appl.
No.: |
12/986,918 |
Filed: |
January 7, 2011 |
Prior Publication Data
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Document
Identifier |
Publication Date |
|
US 20110172475 A1 |
Jul 14, 2011 |
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Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
|
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61293459 |
Jan 8, 2010 |
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Current U.S.
Class: |
585/240; 585/330;
585/241; 585/252; 585/379; 585/300; 585/275; 585/314; 585/310;
585/250; 585/242; 585/440; 585/257 |
Current CPC
Class: |
C07C
15/04 (20130101); C07C 11/02 (20130101); C07C
9/16 (20130101); C07C 1/24 (20130101); C07C
15/02 (20130101); C07C 407/00 (20130101); C10G
29/205 (20130101); C07C 15/08 (20130101); C07C
67/00 (20130101); C10G 3/00 (20130101); C07C
37/20 (20130101); C07C 67/08 (20130101); C07C
45/53 (20130101); C07D 301/19 (20130101); C10G
50/00 (20130101); C07C 51/16 (20130101); C07C
45/28 (20130101); C07C 37/50 (20130101); C10G
69/12 (20130101); C07C 11/167 (20130101); C07C
1/24 (20130101); C07C 11/04 (20130101); C07C
1/24 (20130101); C07C 11/08 (20130101); Y02P
30/20 (20151101); Y02P 20/52 (20151101) |
Current International
Class: |
C07C
1/24 (20060101) |
Field of
Search: |
;585/14,240,254,303,310,324,640,647,241,242,250,252,257,275,300,314,330,379,440
;44/385,398,403,437 ;208/142-145 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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1313083 |
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Apr 1973 |
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GB |
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10-237017 |
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Sep 1998 |
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JP |
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2001-2600 |
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Jan 2001 |
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JP |
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2006-306731 |
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Nov 2006 |
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JP |
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2007-61763 |
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Mar 2007 |
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JP |
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WO 03/053570 |
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Jul 2003 |
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WO |
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WO 03/070671 |
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Aug 2003 |
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WO |
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WO 2005/065393 |
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Jul 2005 |
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WO |
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WO 2005/073172 |
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Aug 2005 |
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WO |
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WO 2005/092821 |
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Oct 2005 |
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WO |
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WO 2007/091862 |
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Aug 2007 |
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WO |
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WO 2008/058664 |
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May 2008 |
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WO |
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WO 2008/113492 |
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Sep 2008 |
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WO |
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WO 2009/038965 |
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Mar 2009 |
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WO |
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WO 2009/039000 |
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Mar 2009 |
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WO |
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WO 2009/039333 |
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Mar 2009 |
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WO |
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WO 2009/039335 |
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Mar 2009 |
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WO |
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WO 2009/039347 |
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Mar 2009 |
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WO |
|
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Primary Examiner: Bullock; In Suk
Assistant Examiner: Pregler; Sharon
Attorney, Agent or Firm: Cooley LLP
Parent Case Text
CROSS REFERENCE TO RELATED APPLICATIONS
This application claims priority to U.S. Provisional Appl. No.
61/293,459, filed Jan. 8, 2010, which is herein incorporated by
reference in its entirety for all purposes.
Claims
We claim:
1. An integrated process for preparing renewable hydrocarbons,
comprising: (a) providing renewable isobutanol and renewable
ethanol; (b) dehydrating the renewable isobutanol, thereby forming
a renewable butene mixture comprising one or more renewable linear
butenes and renewable isobutene; (c) dehydrating the renewable
ethanol, thereby forming renewable ethylene; (d) reacting at least
a portion of the renewable butene mixture and at least a portion of
the renewable ethylene to form one or more renewable
C.sub.3-C.sub.16 olefins; (e) forming renewable hydrogen by one or
more of: (e1) isolating and dehydrogenating at least a portion of
the linear butenes formed in step (b) and/or one or more renewable
C.sub.4-C.sub.16 olefins formed in step (d) thereby forming one or
more renewable C.sub.4-C.sub.16 dienes and renewable hydrogen; (e2)
isolating and dehydrocyclizing at least a portion of one or more
renewable C.sub.6-C.sub.16 olefins formed in step (d), thereby
forming one or more renewable C.sub.6-C.sub.16 aromatics and
renewable hydrogen; (e3) isolating and dehydrocyclizing at least a
portion of one or more renewable C.sub.6-C.sub.16 dienes formed in
step (e1) to form one or more renewable C.sub.6-C.sub.16 aromatics
and renewable hydrogen; and (f) hydrogenating at least a portion of
the renewable C.sub.3-C.sub.16 olefins with the renewable hydrogen
formed in step (e), thereby forming a renewable saturated
hydrocarbon fuel or fuel additive, wherein the amount of said
dehydrogenating and/or dehydrocyclizing in step (e), and/or the
amount of hydrogenating in step (f) are controlled so that the
amount of renewable hydrogen formed in step (e) is essentially
completely consumed in step (f).
2. The integrated process of claim 1, wherein the one or more
renewable linear butenes comprise 2-butene.
3. The integrated process of claim 1, wherein said reacting of step
(d) comprises one or more reactions selected from the group
consisting of disproportionation, metathesis, oligomerization,
isomerization, alkylation, dehydrodimerization, dehydrocyclization,
and combinations thereof.
4. The integrated process of claim 1, wherein said reacting of step
(d) comprises dimerizing at least a portion of the renewable
isobutene, thereby forming a renewable isobutene dimer mixture
comprising at least one C.sub.8 hydrocarbon selected from the group
consisting of a 2,4,4-trimethylpentene, a 2,5-dimethylhexene, and
2,5-dimethylhexadienes, and combinations thereof.
5. The integrated process of claim 1, wherein said reacting of step
(d) comprises trimerizing at least a portion of the renewable
isobutene, thereby forming a renewable isobutene trimer mixture
comprising 2,2,4,6,6-pentamethylheptene.
6. The integrated process of claim 1, wherein said reacting of step
(d) comprises tetramerizing at least a portion of the renewable
isobutene, thereby forming a renewable isobutene tetramer mixture,
wherein the renewable isobutene tetramer mixture comprises
2,2,4,6,6,8,8-heptamethylnonene.
7. The integrated process of claim 1, wherein said reacting of step
(d) comprises isomerizing at least a portion of the renewable
isobutene of step (b) to form an isobutene isomerization mixture
comprising renewable 2-butene, wherein said reacting of step (d)
further comprises disproportionating at least a portion of the
renewable ethylene formed in step (c) and at least a portion of the
renewable 2-butene formed by isomerizing at least a portion of the
renewable isobutene of step (b), thereby forming renewable
propylene.
8. The integrated process of claim 2, wherein said reacting of step
(d) comprises disproportionating at least a portion of the
renewable ethylene formed in step (c) and at least a portion of the
renewable 2-butene formed in step (b), thereby forming renewable
propylene.
9. The integrated process of claim 2, wherein said reacting of step
(d) comprises disproportionating at least a portion of the
renewable ethylene formed in step (c), and at least a portion of
the renewable 2-butene formed in step (b) and renewable 2-butene
formed by isomerizing the renewable isobutene formed in step (b),
thereby forming renewable propylene.
10. The integrated process of claim 1, wherein step (e) comprises
step (e1).
11. The integrated process of claim 10, wherein the one or more
renewable C.sub.4-C.sub.16 dienes formed in step (e1) comprise
butadiene.
12. The integrated process of claim 1, wherein step (e) comprises
step (e2).
13. The integrated process of claim 12, wherein the one or more
renewable C.sub.6-C.sub.16 aromatics formed in step (e2) comprise
renewable p-xylene.
14. The integrated process of claim 1, wherein step (e) comprises
step (e1) and step (e2).
15. The integrated process of claim 1, wherein step (e) comprises
step (e1) and step (e3).
16. The integrated process of claim 1, wherein step (e) comprises
step (e1), step (e2), and step (e3).
17. The integrated process of claim 4, wherein at least a portion
of the renewable isobutene dimer mixture is hydrogenated in step
(f), whereby the renewable saturated hydrocarbon fuel or fuel
additive comprises isooctane, wherein the renewable isobutene dimer
mixture is hydrogenated in step (f), whereby the renewable
saturated hydrocarbon fuel or fuel additive comprises
isooctane.
18. The integrated process of claim 5, wherein at least a portion
of the renewable isobutene trimer mixture is hydrogenated in step
(f), whereby the renewable saturated hydrocarbon fuel or fuel
additive comprises one or more pentamethylheptanes, wherein the
renewable isobutene trimer mixture is hydrogenated in step (f),
whereby the renewable saturated hydrocarbon fuel or fuel additive
comprises one or more pentamethylheptanes.
19. The integrated process of claim 1, wherein said reacting of
step (d) further comprises mixing said renewable butene mixture
and/or said renewable ethylene with at least a portion of a
non-renewable butene and/or a butene mixture and/or non-renewable
renewable ethylene to form one or more C.sub.3-C.sub.16 olefins,
and at least a portion of said one or more C.sub.3-C.sub.16 olefins
are renewable.
Description
BACKGROUND OF THE INVENTION
Conventional transportation fuels and chemicals (e.g., monomers,
polymers, plasticizers, adhesives, thickeners, aromatic and
aliphatic solvents, etc.) are typically derived from non-renewable
raw materials such as petroleum. However, the production,
transportation, refining and separation of petroleum to provide
transportation fuels and chemicals is problematic in a number of
significant ways.
For example, petroleum (e.g., crude oil and/or natural gas)
production poses a number of environmental concerns. First, the
history of petroleum production includes many incidents where there
have been uncontrolled releases of crude petroleum during
exploration and production (e.g., drilling) operations. While many
of these incidents have been relatively minor in scale, there have
been a number of incidents that have been significant in scale and
environmental impact (e.g., BP's Deepwater Horizon incident,
Mississippi Canyon, Gulf of Mexico, 2010).
World petroleum supplies are finite. Thus, as world petroleum
demand has increased (84,337 M bpd worldwide in 2009; US Energy
Information Administration), easily accessible reserves have been
depleted. Accordingly, petroleum exploration and production
operations are more frequently conducted in remote and/or
environmentally sensitive areas (e.g., deepwater offshore, arctic
regions, wetlands, wildlife preserves, etc.). Some remote locations
require highly complex, technically challenging solutions to locate
and produce petroleum reserves (e.g., due to low temperatures,
water depth, etc.). Accordingly, the potential for large-scale
environmental damage resulting from uncontrolled discharge of
petroleum during such complex, technically challenging exploration
and production operations is substantively increased.
In addition, when petroleum is produced in remote areas and/or
areas which do not have infrastructure (e.g., refineries) to
further process petroleum into useful products, the produced
petroleum must be transported (e.g., via pipeline, rail, barge,
ship, etc.), often over significant distances, to terminal points
where the petroleum products may be refined and/of processed.
Transportation of petroleum is also an operation with associated
risk of accidental discharge of petroleum in the environment, with
concomitant environmental damage, and there have been a number of
significant incidents (e.g., Exxon's Valdez tanker spill, Prince
William Sound, Ak., 1989). Furthermore, much of the world's proven
petroleum reserves are located in regions which are politically
unstable. Accordingly, supplies of petroleum from such regions may
be uncertain since production of petroleum or transportation of
petroleum products from such regions may be interrupted.
Petroleum is a complex mixture of chemical compounds. Crude
petroleum comprises chemical entities from very the simple, e.g.,
helium and methane prevalent in natural gas, to the complex, e.g.,
asphaltenes and heterocyclic organic compounds prevalent in heavy,
sour crude oil. Furthermore, crude petroleum is typically
co-produced with varying amounts of formation water (e.g., water
from the rock formation from which the petroleum was produced),
often as stable emulsion, with salts, metals and other
water-soluble compounds dissolved in the formation water. Crude oil
may also contain varying amounts of particulate salts, metals,
sediments, etc. Accordingly, crude oil streams are typically
desalted, then allowed to settle and phase-separate into crude and
water fractions, reducing the water content of the crude and the
level of undesired components such as salts, metals, silt,
sediment, etc. which may be present in the crude. Such undesired
components are generally problematic in further processing and/or
refining of petroleum into commercially useful fractions. For
example, certain unit operations in the refining process may be
sensitive to water, salt or sediment. Further, piping, storage and
process vessels employed in the transport, storage and processing
of petroleum is prone to corrosion, which may be accelerated and/or
exacerbated by the presence of salt and/or water in the petroleum
feedstock.
Desalting processes typically require the use of large quantities
of water, which also may be heated, to extract salt and soluble
metals from the crude oil. Further, the crude stream to be desalted
is also generally heated to effect mixing with the extraction
water. The resulting emulsions may then be treated with
demulsifying agent and allowed to settle prior to further
processing. Such desalting (and settling) may be time consuming,
and may require (i) large quantities of water to extract the
undesirable components, (ii) large amounts of energy to heat the
water and/or crude stream(s) to effect mixing, and (iii) the use of
substantial quantities of chemical agents to treat the crude (e.g.,
demulsifiers). As a result, large quantities of contaminated water
are produced in desalting operation which must be treated to remove
residual oil, dissolved salts, metals, water-soluble organics,
demulsifiers, etc.
Furthermore, crude petroleum from regions, different subterranean
reservoirs within a region, or even from different strata within a
single field may have different chemical compositions. For example,
crude oils can range from "light, sweet" oils which generally flow
easily, and have a higher content of lower molecular weight
hydrocarbons and low amounts of contaminants such as sulfur, to
heavy, sour oils, which may contain a large fraction of high
molecular weight hydrocarbons, large amounts of salts, sulfur,
metals and/or other contaminants, and may be very viscous and
require heating to flow. Furthermore, the relative amounts of the
constituent fractions (e.g., light, low molecular weight
hydrocarbons vs. heavier, higher molecular weight hydrocarbons) of
the various grades or types of crude oil varies considerably. Thus,
the chemical composition of the feedstock for a refinery may vary
significantly, and as a result, the relative amounts of the
hydrocarbon streams produced may vary as a function of the crude
feed.
Once the crude feedstock is sufficiently treated to remove
undesired impurities or contaminants, it can then be subject to
further processing and/or refining. The crude feedstock is
typically subject to an initial distillation, wherein the various
fractions of the crude are separated into distillate fractions
based on boiling point ranges. This is a particularly energy
intensive process, as this separation is typically conducted on a
vast scale, and most or all of the feedstock is typically heated in
the distillation unit(s) to produce various distillate fractions.
Furthermore, since the crude composition is quite complex,
containing hundreds of compounds (if not more), each fraction may
contain many different compounds, and the composition and yield of
each distillate fraction may vary depending on the type and
composition of crude feedstock. Depending on the desired product
distribution on the back end of a refining operation, a number of
additional refining steps may be performed to further refine and/or
separate the distillate streams, each of which may require
additional equipment and energy input.
For example, higher boiling fractions from an initial distillation
may be subject to further distillation (e.g., under vacuum) to
separate the mixture even further. Alternatively, heavy fractions
from an initial distillation may be subject to "cracking" (e.g.,
catalytic cracking) at high temperatures to reduce the average
molecular weight of the components of the feed stream. Since
lighter hydrocarbon fractions (e.g., containing less than 20 carbon
atoms) generally have greater commercial value and utility than
heavier fractions (e.g., those containing more than 20 carbon
atoms), cracking may be performed to increase the value and/or
utility of a stream from an initial distillation. However, such
cracking operations are typically very energy intensive since high
temperatures (e.g., 500.degree. C.) are generally required to
effect the breakdown of higher molecular weight hydrocarbons into
lower molecular weight components. Furthermore, the output from
such cracking operations is also a complex mixture, and
accordingly, may require additional separation (e.g., distillation)
to separate the output stream into useful and/or desired fractions
having target specifications, e.g., based on boiling point range or
chemical composition.
Accordingly, the various components streams produced from petroleum
refining and/or processing are generally mixtures. The homogeneity
or heterogeneity of those mixtures may be a factor of the character
of the crude feedstock, the conditions at which separations are
conducted, the characteristics of a cracked stream, and the
specifications of an end user for purity of a product stream.
However, in practical terms, higher purity streams will require
more rigorous separation conditions to isolate a desired compound
from related compounds with similar boiling points (e.g., compounds
having boiling points within 20, 10, or 5.degree. C. of each
other). Such rigorous separations generally require large process
units (e.g., larger distillation columns) to separate more closely
related compounds (e.g., compounds which have relatively close
boiling points).
Furthermore, in addition to the above-described environmental
concerns and energy/infrastructure costs associated with petroleum
production and refining, there is mounting concern that the use of
petroleum as a basic raw material in the production of chemical
feedstocks and fuels contributes to environmental degradation
(e.g., global warming) via generation and/or release of oxides of
carbon. For example, burning a gallon of typical gasoline produces
over 19 pounds of carbon dioxide. Because no carbon dioxide is
consumed by a refinery in the manufacture of gasoline, the net
carbon dioxide produced from burning a gallon of petroleum-derived
gasoline is at least as great as the amount of carbon contained in
the fuel, and is typically higher when the combustion of additional
petroleum required to power the refinery (e.g., for separation of
petroleum to produce the gasoline) and to power the transportation
vehicles, pumps along pipelines, ships, etc. that bring the fuel to
market is considered. Likewise, the production of basic chemicals
(e.g., ethylene, propylene, butenes, butadiene, and aromatics such
as benzene, toluene, and xylenes) from petroleum does not consume
carbon dioxide, and the energy required to power the refinery to
produce such chemicals and the transportation vehicles to deliver
those chemicals also generate carbon dioxide.
In contrast to fossil fuels and petroleum derived chemicals, the
net carbon dioxide produced by burning a gallon of biofuel or
biofuel blend, or by producing biomass derived chemicals is less
than the net carbon dioxide produced by burning a gallon of
petroleum derived fuel or in producing chemicals from petroleum. In
addition, biomass-derived chemical and fuel production has far
fewer environmental hazards associated with it, since production of
biomass-derived fuels requires no drilling operations. Further,
biomass-derived chemical and fuel facilities can be located in a
wide range of locations relative to petroleum refineries,
essentially almost anywhere appropriate feedstocks are available
(e.g., where sufficient amounts of suitable plant matter are
available). Thus, the requirement for transport of feedstock can
minimized, as are the associated energy costs of such transport.
Further, even if transport of raw materials is needed, the
environmental hazards of a spill of a typical biomass feedstock
(e.g., corn) are negligible. Furthermore, biomass-derived product
streams are typically far less complex mixtures than product
streams from petroleum refining operations. Thus, far less energy
may be required to obtain high purity product streams from
biomass-based chemical production operations.
However, most biofuels and biomass-derived organic chemicals are
produced from relatively expensive feedstocks (compared to
petroleum), or are produced by processes which may be relatively
inflexible or cannot readily adapt to changes in raw material costs
or product prices. As a result, many biomass-based processes have
difficulty competing economically with petroleum-based (e.g.
refinery) processes.
SUMMARY OF THE INVENTION
The present invention is directed to an integrated process for
producing a mixture of renewable biofuels and/or biofuel
precursors, as well as a variety of different renewable chemicals
from renewable ethanol and renewable isobutanol.
In various embodiments, the present invention is directed to an
integrated process for preparing renewable hydrocarbons from
renewable isobutanol and renewable ethanol, comprising dehydrating
the renewable isobutanol, thereby forming a renewable butene
mixture comprising one or more renewable linear butenes and
renewable isobutene; dehydrating the renewable ethanol, thereby
forming renewable ethylene; and reacting at least a portion of the
renewable butene mixture and at least a portion of the renewable
ethylene to form one or more renewable C.sub.3-C.sub.16
olefins.
In other embodiments, the integrated process further comprises
forming renewable hydrogen by one or more of: (i) dehydrogenating
at least a portion of linear butenes formed by dehydrating
renewable isobutanol and/or one or more renewable C.sub.4-C.sub.16
olefins isolated from renewable C.sub.3-C.sub.16 olefins formed
from reacting at least a portion of a renewable butene mixture and
at least a portion of a renewable ethylene stream, thereby forming
one or more renewable C.sub.4-C.sub.16 dienes and renewable
hydrogen; (ii) dehydrocyclizing at least a portion of one or more
renewable C.sub.6-C.sub.16 olefins isolated from the renewable
C.sub.3-C.sub.16 olefins formed from reacting at least a portion of
a renewable butene mixture and at least a portion of a renewable
ethylene stream, thereby forming one or more renewable
C.sub.6-C.sub.16 aromatics and renewable hydrogen; (iii)
dehydrocyclizing at least a portion of one or more renewable
C.sub.6-C.sub.16 dienes isolated from the renewable
C.sub.4-C.sub.16 dienes formed by dehydrogenating at least a
portion of linear butenes formed by dehydrating renewable
isobutanol and/or one or more renewable C.sub.4-C.sub.16 olefins
isolated from renewable C.sub.3-C.sub.16 olefins formed from
reacting at least a portion of a renewable butene mixture and at
least a portion of a renewable ethylene stream, to form one or more
renewable C.sub.6-C.sub.16 aromatics and renewable hydrogen. The
integrated process may also comprise hydrogenating at least a
portion of the renewable C.sub.3-C.sub.16 olefin stream with
renewable hydrogen, thereby forming a renewable saturated
hydrocarbon fuel or fuel additive.
In still other embodiments, the process of the present invention
further comprises controlling the total amount of renewable
hydrogen produced by said dehydrogenating and/or dehydrocyclizing,
so that the total amount of renewable hydrogen produced is consumed
by hydrogenating the renewable C.sub.3-C.sub.16 olefins.
In other embodiments, the process of the present invention further
comprises forming the one or more renewable C.sub.3-C.sub.16
olefins by disproportionation, metathesis, oligomerization,
isomerization, alkylation, and combinations thereof.
The present integrated processes provide a flexible,
environmentally sound method or system for producing
biomass-derived chemicals, fuels and/or fuel blends. The present
integrated process may provide product streams which can be readily
and flexibly adapt to different biomass feedstocks, and may produce
different mixtures of renewable products based on market demand.
The present integrated process may also advantageously provide
product streams having well-defined, predictable chemical
compositions.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a schematic diagram of the formation of butene isomers
from the dehydration of isobutanol.
FIG. 2 is a schematic of a unit operation for dehydrating
isobutanol to isobutene (isobutylene).
FIG. 3 is a plot of butene isomer equilibrium composition as a
function of dehydration temperature.
FIG. 4 is a schematic of a method of preparing C.sub.5 dienes
(e.g., isoprene) from C.sub.4 olefins (e.g., isobutene) by the
Prins reaction.
FIG. 5 is a schematic of the dehydrogenation of n-butane.
FIG. 6 is a schematic of the dehydrogenation of 1-butene to
1,3-butadiene.
FIG. 7 is a schematic of the acid-catalyzed rearrangement of
isobutene
FIG. 8 is a schematic of the formation of benzene, acetone,
propylene oxide, phenol, and bisphenol A from renewable
propylene.
FIG. 9 is a schematic of the formation of butyraldehyde,
isobutyraldehyde, n-butanol, isobutanol, 2-ethylhexanol, and
2-ethylhexanoic acid from propylene and ethylene.
FIG. 10 is a schematic of an integrated process for converting
renewable isobutanol to renewable p-xylene.
DETAILED DESCRIPTION OF THE INVENTION
All documents cited herein are incorporated by reference in their
entirety for all purposes to the same extent as if each individual
document was specifically and individually indicated to be
incorporated by reference.
DEFINITIONS
"Renewably-based" or "renewable" denote that the carbon content of
the renewable alcohol (and olefin, di-olefin, etc., or subsequent
products prepared from renewable alcohols, olefins, di-olefins,
etc. as described herein), is from a "new carbon" source as
measured by ASTM test method D 6866-05, "Determining the Biobased
Content of Natural Range Materials Using Radiocarbon and Isotope
Ratio Mass Spectrometry Analysis", incorporated herein by reference
in its entirety. This test method measures the .sup.14C/.sup.12C
isotope ratio in a sample and compares it to the .sup.14C/.sup.12C
isotope ratio in a standard 100% biobased material to give percent
biobased content of the sample. "Biobased materials" are organic
materials in which the carbon comes from recently (on a human time
scale) fixated CO.sub.2 present in the atmosphere using sunlight
energy (photosynthesis). On land, this CO.sub.2 is captured or
fixated by plant life (e.g., agricultural crops or forestry
materials). In the oceans, the CO.sub.2 is captured or fixated by
photosynthesizing bacteria or phytoplankton. For example, a
biobased material has a .sup.14C/.sup.12C isotope ratio greater
than 0. Contrarily, a fossil-based material has a .sup.14C/.sup.12C
isotope ratio of about 0. The term "renewable" with regard to
compounds such as alcohols or hydrocarbons (olefins, di-olefins,
polymers, etc.) also refers to compounds prepared from biomass
using thermochemical methods (e.g.; Fischer-Tropsch catalysts),
biocatalysts (e.g., fermentation), or other processes, for example
as described herein.
A small amount of the carbon atoms of the carbon dioxide in the
atmosphere is the radioactive isotope .sup.14C. This .sup.14C
carbon dioxide is created when atmospheric nitrogen is struck by a
cosmic ray generated neutron, causing the nitrogen to lose a proton
and form carbon of atomic mass 14 (.sup.14C), which is then
immediately oxidized to carbon dioxide. A small but measurable
fraction of atmospheric carbon is present in the form of
.sup.14CO.sub.2. Atmospheric carbon dioxide is processed by green
plants to make organic molecules during the process known as
photosynthesis. Virtually all forms of life on Earth depend on this
green plant production of organic molecules to produce the chemical
energy that facilitates growth and reproduction. Therefore, the
.sup.14C that forms in the atmosphere eventually becomes part of
all life forms and their biological products, enriching biomass and
organisms which feed on biomass with .sup.14C. In contrast, carbon
from fossil fuels does not have the signature .sup.14C:.sup.12C
ratio of renewable organic molecules derived from atmospheric
carbon dioxide. Furthermore, renewable organic molecules that
biodegrade to CO.sub.2 do not contribute to global warming as there
is no net increase of carbon emitted to the atmosphere.
Assessment of the renewably based carbon content of a material can
be performed through standard test methods, e.g. using radiocarbon
and isotope ratio mass spectrometry analysis. ASTM International
(formally known as the American Society for Testing and Materials)
has established a standard method for assessing the biobased
content of materials. The ASTM method is designated ASTM-D6866.
The application of ASTM-D6866 to derive "biobased content" is built
on the same concepts as radiocarbon dating, but without use of the
age equations. The analysis is performed by deriving a ratio of the
amount of radiocarbon (.sup.14C) in an unknown sample compared to
that of a modern reference standard. This ratio is reported as a
percentage with the units "pMC" (percent modern carbon). If the
material being analyzed is a mixture of present day radiocarbon and
fossil carbon (containing very low levels of radiocarbon), then the
pMC value obtained correlates directly to the amount of biomass
material present in the sample.
Throughout the present specification, reference to alcohols,
olefins, di-olefins, etc., and higher molecular weight materials
(e.g., isooctene/isooctane, polymers, copolymers, etc.) made from
such compounds is synonymous with "renewable" alcohols, "renewable"
olefins, "renewable" di-olefins, etc., and "renewable" materials
(e.g., "renewable" isooctene/isooctane, "renewable" polymers,
"renewable" copolymers, etc.) unless otherwise indicated. Unless
otherwise specified, all such chemicals produced by the integrated
processes described herein are renewable unless explicitly stated
otherwise.
Throughout the present specification, the terms "olefin" and
"alkene" are used interchangeably to refer to a hydrocarbon having
at least one carbon-carbon double bond. Alkenes or olefins having
two carbon-carbon double bonds can be referred to as dienes, and if
the two carbon-carbon double bonds are adjacent in the molecule
(e.g., four adjacent sp.sup.2 carbon atoms), the molecule can be
termed a conjugated diene.
The renewable alcohols, olefins, di-olefins, polymers, aliphatic
and aromatic organic compounds, etc. of the present invention have
pMC values of at least about 1, 5, 10, 15, 20, 25, 30, 35, 40, 45,
50, 55, 60, 65, 70, 75, 80, 85, 90, 95, 100, inclusive of all
values and subranges therebetween.
Throughout the present specification, the term "about" may be used
in conjunction with numerical values and/or ranges. The term
"about" is understood to mean those values near to a recited value.
For example, "about 40 [units]" may mean within .+-.25% of 40
(e.g., from 30 to 50), within .+-.20%, .+-.15%, .+-.10%, .+-.9%,
.+-.8%, .+-.7%, .+-.6%, .+-.5%, .+-.4%, .+-.3%, .+-.2%, .+-.1%,
less than .+-.1%, or any other value or range of values therein or
therebelow. Furthermore, the phrases "less than about [a value]" or
"greater than about [a value]" should be understood in view of the
definition of the term "about" provided herein.
Throughout the present specification, numerical ranges are provided
for certain quantities. It is to be understood that these ranges
comprise all subranges therein. Thus, the range "from 50 to 80"
includes all possible ranges therein (e.g., 51-79, 52-78, 53-77,
54-76, 55-75, 60-70, etc). Furthermore, all values within a given
range may be an endpoint for the range encompassed thereby (e.g.,
the range 50-80 includes the ranges with endpoints such as 55-80,
50-75, etc.).
Throughout the present specification, the words "a" or "an" are
understood to mean "one or more" unless explicitly stated
otherwise. Further, the words "a" or "an" and the phrase "one or
more" may be used interchangeably.
Overall Process
In various embodiments, the present invention is directed to an
integrated process for preparing various renewable hydrocarbons
from renewable ethanol and renewable isobutanol. The renewable
ethanol and isobutanol can be sold as commodity chemicals directly,
or dehydrated to their respective olefins (e.g. ethylene and
isobutene and one or more renewable linear butenes--typically a
mixture of isobutene, 1-butene and cis/trans-2-butene). The
renewable ethylene and renewable butenes can then also either be
sold directly, or further processed (e.g., separated or reacted) in
a variety of different ways to produce a wide variety of renewable
hydrocarbon product streams. In certain embodiments, further
processing may comprise mixing the renewable ethylene and/or
butenes with ethylene and/or butylene produced by conventional
methods (e.g., petroleum cracking) to produce an array of
hydrocarbon compounds comprising renewable carbon. Accordingly,
such compounds, while not composed solely of renewable carbon,
still comprise at least some renewable carbon, with concomitant
environmental advantages as described herein.
For example, one renewable hydrocarbon product stream is renewable
ethylene, produced from dehydration of renewable ethanol. The
renewable ethylene produced thereby is generally of very high
purity, and is easily separated from the unreacted feedstock of the
dehydration reaction (typically aqueous ethanol and catalyst) by
removal of the produced ethylene from the reaction space as a gas
stream. The renewable ethylene can then be either sold directly as
a feedstock, or subsequently converted to higher value renewable
hydrocarbons, such as higher molecular weight olefins produced by
oligomerization reactions (e.g. dimers, trimers, etc.), polymerized
to form renewable polyethylene, oxidized form renewable ethylene
oxide (which can be subsequently be polymerized to form renewable
polyethylene oxide, or converted to other renewable polyethylene
oxide derivatives), converted to dichloroethane (for subsequent
conversion to vinyl chloride and polymerization thereof), used as a
renewable feedstock for alkylating other olefins or aromatics
(e.g., alkylation of benzene to produce ethylbenzene), etc.
Another renewable hydrocarbon product stream is renewable butene,
produced from the dehydration of renewable isobutanol. The
renewable butene formed thereby is typically a tunable mixture of
butene isomers, which is easily separated from the isobutanol feed
to the dehydration reaction, and can be sold directly as a mixture,
reacted as a mixture to form other hydrocarbons (e.g.,
polybutenes), or the mixture of renewable butene isomers can be
separated (e.g., by distillation, by selective conversion, etc.)
into individual butene isomers, which can then either be sold
individually as feedstocks, polymerized (e.g. to renewable
polyisobutylene or butene copolymers), oligomerized (e.g.,
dimerized, trimerized, etc.) to form higher molecular weight
olefins (e.g. isooctene or pentamethylheptenes), isomerized (e.g.
isobutene isomerized to linear butenes, 1-butene isomerized to
2-butene, or 2-butene isomerized to 1-butene, etc.), dehydrogenated
(e.g. to butadiene), as well as combinations of such processes,
etc. In particular, isobutene dimers and trimers can be
hydrogenated to provide, e.g., renewable isooctane and renewable
pentamethylheptenes, both of which are useful as, e.g., renewable
transportation fuels or renewable additives for transportation
fuels.
In addition, the renewable olefins provided by the integrated
processes described herein can also be reacted together, e.g.,
disproportionated, to provide olefins of varying carbon number
(e.g., 3, 5, 7, etc.). For example, renewable ethylene and
renewable 2-butene produced as described herein can be
disproportionated using appropriate conditions (e.g., an
appropriate metathesis catalyst) to provide renewable propylene.
Renewable propylene produced by such a disproportionation process
can be sold directly as a feedstock, or subsequently converted to
other higher value renewable hydrocarbons by, e.g., oligomerization
to produce higher olefins (e.g. dimers, trimers, etc.),
polymerization to form polypropylene, oxidation to form propylene
oxide (which can be subsequently be polymerized to form renewable
polypropylene oxide, or converted to other renewable polypropylene
oxide derivatives), oxidation to form acrylic acid (which may be
further reacted to form a range of commercially significant acrylic
esters), reaction with ammonia and oxygen to form acrylonitrile,
reaction with benzene to produce acetone and phenol (e.g., via the
cumene process), etc.
Similarly, disproportionation and/or oligomerization reactions of
ethylene, butenes, propylene and oligomers thereof can be combined
in various ways to produce a range of olefins having a desired
number of carbon atoms. The various mono-olefins produced by such
reactions can be dehydrogenated to form dienes or other polyenes
(trienes, etc.) and renewable hydrogen as a valuable co-product. In
addition, olefins and/or polyenes produced by these reactions can
also be dehydrocyclized to form cyclic olefins (e.g., cyclohexene)
or aromatics (e.g., benzene, xylenes), which also produces
renewable hydrogen. Furthermore, the reactivity of olefins is
suited to selective introduction of heteroatoms into the
above-described olefins (e.g., oxygen, nitrogen, halogens, etc.),
allowing access to a broad array of derivatives.
Thus, beginning with simple, renewable ethanol and isobutanol
feedstocks, the integrated process of the present invention can
provide essentially all of the commercially important hydrocarbons
currently produced in petrochemical refineries (e.g., ethylene,
propylene, butenes, butadiene, xylenes such as p-xylene, toluene,
and benzene), and when coupled with additional processes, can
produce virtually any fuel or chemical. In particular, the present
invention provides a method for the production of benzene and
xylene, commodity chemicals which serve as the building blocks from
a vast array of intermediates and finished products. Furthermore,
when the ethanol and isobutanol feedstocks are renewable, produced
from biomass or other biological sources, the integrated process of
the present invention can produce renewable hydrocarbons
corresponding to the petroleum-derived hydrocarbons produced in a
conventional petroleum refinery in a more environmentally sound and
sustainable fashion. Further still, even in cases where the use of
solely renewable feedstocks is not feasible and/or economical,
supplementing traditional petroleum-derived hydrocarbon feedstocks
(e.g., ethylene, butenes, etc.) with renewable feedstocks in
integrated chemical processing and/or manufacturing operations can
still provide substantive advantages (e.g., reduced environmental
impact, carbon footprint, etc.) relative to traditional,
"petroleum-only" operations.
In contrast to the present methods, petroleum-derived ethylene,
butenes and/or propylene are typically produced in catalytic
cracking of higher molecular weight hydrocarbons, as component in a
complex mixture of hydrocarbons. Such mixtures typically include,
among a range of product compounds, low molecular weight olefins
such as propylene, butene, and butadiene, which may be difficult to
separate due to their similar boiling points. Accordingly,
purifying such a stream to produce a high-purity ethylene,
propylene, butenes, or butadiene fractions is typically an energy
intensive process. In fact, mixtures of ethylene, propylene, butene
and butadiene are often sold directly as liquefied mixtures by
refineries, as a commodity, rather than separating the individual
fractions, due to the costs of equipment and energy required to
separate the various components of such mixtures. However, if
desired, the present integrated processes can provide such a
mixture analogous to that provided by refinery cracking processes,
thus supplying a typical refinery product for end users who rely on
such mixed feedstocks. Furthermore, mixtures of hydrocarbons
produced by the present methods typically have a well-defined
composition due to the limited number of possible products
associated with each individual process or reactive step.
Accordingly, the present integrated methods may provide higher
purity products requiring less additional processing and/or energy
to separate. Alternatively, the present integrated process may
provide mixed streams with simpler, well-defined compositions.
The relative amounts of product outputs produced in the processes
described herein can be flexibly adjusted in various ways to adjust
to, e.g., changing market demand for specific product streams or to
maximize the overall value of the products produced. For example,
the relative amounts of ethanol and isobutanol supplied to the
process of the present invention can be adjusted, or the relative
amounts of, e.g., ethylene and isobutene (and/or linear butenes,
etc.) supplied to various unit operations can be adjusted to vary
the product mix, and thereby maximize the economic value of the
products produced. Since the catalysts described herein for
producing renewable ethanol and renewable isobutanol use similar
biomass raw material, the relative output from a given unit input
of biomass can be adjusted as desired to a higher or lower fraction
of either ethanol or isobutanol. As a result, varying demand for
products produced downstream can be accommodated by adjusting
relative production of ethanol and isobutanol (and intermediates
and/or products subsequently formed therefrom).
For example, if market demand and/or market price for ethylene (or
products formed therefrom) is high, the relative amount of ethanol
feedstock can be increased, and accordingly, the amount of ethylene
produced via dehydration of ethanol can be increased. Similarly, if
market demand and/or market price for butylene(s) (or products
formed therefrom) is high, the relative amount of isobutanol
feedstock can be increased, and accordingly, the amount of
butylene(s) produced via dehydration of isobutanol can be
increased. In another case, if market demand and/or market price
for propylene (or products prepared from propylene) increases, the
relative amounts of renewable ethanol and isobutanol fed into the
process can be adjusted to optimize the relative amounts of
ethylene and 2-butene feedstocks for subsequent disproportionation
to propylene. Similarly, in situations where fuel prices are high
and/or fuel demand is high, the amount of isobutanol relative to
ethanol fed into the process of the present invention can be
increased to maximize production of isooctene and/or
pentamethylheptenes (dimer and trimer of isobutylene), and
optionally the relative amount of olefins fed to dehydrocyclization
could be increased in order to supply the necessary hydrogen to
reduce the isooctene and/or pentamethylheptenes to the respective
isooctane and pentamethylheptanes.
Alternatively, if it is desirable to maximize the production of
aromatics and dienes such as butadiene, the process can be adjusted
to maximize production of butadiene and aromatics such as benzene
and xylenes (and/or products downstream such as styrene, cumene,
etc.), and the excess hydrogen produced from dehydrogenation of
linear butenes to butadiene or aromatic-forming
cyclodehydrogenations can be sold or utilized to hydrogenate
isooctene and/or pentamethylheptenes to isooctane (e.g., for
gasoline) and/or pentamethylheptanes (e.g., for jet fuel). Thus,
the amount and composition of feedstocks fed to the present
integrated process, and the relative quantities of produced product
in the various unit operations described herein can be increased or
decreased to maximize the overall value of the products produced
while ensuring complete utilization of the renewable carbon and
optionally hydrogen produced in the integrated process.
In certain embodiments, the process of the present invention
utilizes most or all of all the carbon in the ethanol and
isobutanol feedstock, and most or all of the renewable hydrogen
produced by dehydrogenation and/or dehydrocyclization reactions, to
form a renewable saturated hydrocarbon fuel or fuel active product
stream and one or more additional high-value product streams.
Within the constraint of complete utilization of carbon and
hydrogen produced in the process, the amount of saturated
hydrocarbon fuel or fuel additive and the selection and amount of
other high-value product streams can be adjusted to meet variations
in market demand and market value for different product
streams.
Production of Alcohols
The processes of the present invention for making renewable
compositions, as described herein, typically begin with the
formation of renewable alcohols (e.g., renewable ethanol and
renewable isobutanol), e.g., from biomass. The term "formation from
biomass" includes any combination of methods including
fermentation, thermochemical (e.g., Fischer-Tropsch),
photosynthesis, etc. Renewable alcohol (e.g., ethanol and
isobutanol) streams can be prepared from biomass, by the same
method, or by different methods, or portions of the ethanol and/or
isobutanol can be prepared by a combination of different methods. A
range of renewable alcohols, e.g., ethanol, 1-butanol, 2-butanol,
isobutanol, tert-butanol, pentanols, etc. (and the corresponding
renewable olefins or other chemicals) may be produced and employed
in the integrated processes described herein,
When renewable ethanol and renewable isobutanol are formed by
fermentation, the feedstock for the fermentation process can be any
suitable fermentable feedstock known in the art, for example sugars
derived from agricultural crops such as sugarcane, corn, etc.
Alternatively, the fermentable feedstock can be prepared by the
hydrolysis of biomass, for example lignocellulosic biomass (e.g.
wood, corn stover, switchgrass, herbiage plants, ocean biomass,
etc.). The lignocellulosic biomass can be converted to fermentable
sugars by various processes known in the art, for example acid
hydrolysis, alkaline hydrolysis, enzymatic hydrolysis, or
combinations thereof. In such processes, the carbohydrate component
of the biomass (e.g. cellulose and hemicellulose) are broken down
by hydrolysis to their constituent sugars, which can then be
fermented by suitable microorganisms as described herein to provide
ethanol or isobutanol.
Typically, woody plants comprise about 40-50% cellulose, 20-30%
hemicellulose, and 20-28% lignin, with minor amounts of minerals
and other organic extractives. The cellulose component is a
polysaccharide comprising glucose monomers coupled with
.beta.-1,4-glycoside linkages. The hemicellulose component is also
a polysaccharide, but comprising various five-carbon sugars
(usually xylose and arabinose), six-carbon sugars (galactose,
glucose, and mannose), and 4-O-methyl glucuronic acid and
galacturonic acid residues. The cellulose and hemicellulose
components are hydrolyzed to fermentable five- and six-carbon
sugars which can then be used as a feedstock for the fermentation
as described herein. Residual carbon compounds, lignin (a highly
branched polyphenolic substance), and organic extractives (e.g.,
waxes, oils, alkaloids, proteins, resins, terpenes, etc.) can be
separated from the sugars at various stages of the hydrolysis
process and utilized in various ways, for example, burned has a
fuel to provide energy/heat for the fermentation process and/or for
subsequent processes (e.g., dehydration, oligomerization,
dehydrogenation, etc.).
In one embodiment, the ethanol and isobutanol are both formed by
one or more fermentation steps as described herein. Any suitable
microorganism can be used to prepare renewable ethanol and
butanols. Ethanol can be produced by microorganisms known in the
art such as Saccharomyces cerevisiae. Butanols can be produced, for
example, by the microorganisms described in U.S. Patent Publication
Nos. 2007/0092957, 2008/0138870, 2008/0182308, 2007/0259410,
2007/0292927, 2007/0259411, 2008/0124774, 2008/0261230,
2009/0226991, 2009/0226990, 2009/0171129, 2009/0215137,
2009/0155869, 2009/0155869, 2008/02745425, etc. Additionally,
butanols and other higher alcohols are produced by yeasts during
the fermentation of sugars into ethanol. These fusel alcohols are
known in the art of industrial fermentations for the production of
beer and wine and have been studied extensively for their effect on
the taste and stability of these products. Recently, production of
fusel alcohols using engineered microorganisms has been reported
(U.S. Patent Application No. 2007/0092957, and Nature 2008 (451)
86-89).
Renewable ethanol and renewable isobutanol prepared by fermentation
are, in most embodiments, produced in fermentors and/or under
conditions optimal for fermentation of the respective alcohol. That
is, renewable ethanol is produced in one or more fermentors
optimized for production of ethanol and operated under conditions
optimized for the production of ethanol (e.g., using microorganisms
which produce high yields of ethanol, a fermentable feedstock with
suitable nutrients optimal for ethanol-producing microorganisms,
temperature conditions and ethanol recovery unit operations
optimized for ethanol production, etc.). Likewise, renewable
isobutanol is produced in one or more fermentors under conditions
optimized for the production of isobutanol (e.g., using
microorganisms which produce high yields of isobutanol, a
fermentable feedstock with suitable nutrients optimal for
isobutanol-producing microorganisms, temperature conditions and
isobutanol recovery unit operations optimized for isobutanol
production, etc.). In particular embodiments, ethanol is produced
in a conventional ethanol fermentation plant and isobutanol is
produced in an ethanol fermentation plant retrofitted for the
production of isobutanol, for example as described in US
2009/0171129.
In one embodiment, the retrofitted ethanol plant includes an
optional pretreatment unit, multiple fermentation units, and a beer
still to produce isobutanol. The isobutanol is produced by
optionally pretreating a feedstock (e.g., ground corn) to form
fermentable sugars in the pretreatment unit. A suitable
microorganism, as described herein, is cultured in a fermentation
medium comprising the fermentable sugars in one or more of the
fermentation units to produce isobutanol. The isobutanol can be
recovered from the fermentation medium as described herein, and as
described in US 2009/0171129.
Renewable ethanol and butanols can also be prepared using various
other methods such as conversion of biomass by thermochemical
methods, for example by gasification of biomass to synthesis gas
followed by catalytic conversion of the synthesis gas to alcohols
in the presence of a catalyst containing elements such as copper,
aluminum, chromium, manganese, iron, cobalt, or other metals and
alkali metals such as lithium, sodium, and/or potassium (Energy and
Fuels 2008 (22) 814-839). The various alcohols, including ethanol
and butanols can be separated from the mixture by distillation and
used to prepare renewable ethylene or renewable butenes, or
compounds derived from renewable ethylene and/or butenes as
described herein. Alcohols other than ethanol and isobutanol can be
recovered and utilized as feedstocks for other processes, burned as
fuel or used as a fuel additive, etc.
Alternatively, renewable ethanol and butanols can be prepared
photosynthetically, e.g., using cyanobacteria or algae engineered
to produce isobutanol, isopentanol, and/or other alcohols (e.g.,
Synechococcus elongatus PCC7942 and Synechocystis PCC6803; see
Angermayr et al., Energy Biotechnology with Cyanobacteria, Curr
Opin Biotech 2009 (20) 257-263; Atsumi and Liao, Nature
Biotechnology 2009 (27) 1177-1182; and Dexter et al., Energy
Environ. Sci. 2009 (2), 857-864, and references cited in each of
these references). When produced photosynthetically, the
"feedstock" for producing the resulting renewable alcohols is
light, water and CO.sub.2 provided to the photosynthetic organism
(e.g., cyanobacteria or algae).
Higher alcohols other than butanols or pentanols produced during
fermentation (or other processes as described herein for preparing
renewable ethanol and butanols) may be removed from the ethanol or
butanol prior to carrying out subsequent unit operations (e.g.,
dehydration). The separation of these higher alcohols from the
butanol(s) (e.g. isobutanol) or pentanol(s) (e.g. 1-pentanol,
2-pentanol, 3-pentanol, branched or cyclic pentanols, etc.) can be
effected using known methods such as distillation, extraction, etc.
Alternatively, these higher alcohols can remain mixed in the
butanol(s) or pentanol(s), and can be removed after subsequent
processing. For example, any higher alcohols mixed in with
isobutanol can be dehydrated with the isobutanol stream to the
corresponding olefins, then separated from the mixed butenes. The
determination of whether to remove such higher alcohols prior to
dehydration, or to remove the corresponding olefin after
dehydration (or the corresponding dehydrogenation
byproducts/co-products) generally depends on the relative ease and
cost of the respective separations and the relative value of the
byproducts/co-products. In some cases, the amounts of such
by-products may be low enough that removal is uneconomic and a
product olefin stream may be used directly with such minor
impurities if a subsequent product is tolerant to such impurities.
For example, subsequent the polymerization of a product mixed
butene stream (and the specification of a product polymer produced
thereby) may be such that minor amounts of, e.g., pentenes or other
olefins, may be acceptable, and separation of those minor
components may be unnecessary. Alternatively, in certain cases,
higher alcohols such as pentanols (e.g., 1-pentanol, 2-pentanol,
3-pentanol, branched or cyclic pentanols, etc.) may be produced in
sufficient quantities for use in the present integrated processes.
For example, higher alcohols, e.g., linear pentanols in sufficient
amounts and subject to subsequent reaction/processing to provide an
additional feedstock (e.g., pentenes, pentadienes, etc.) for the
present integrated processes. Other higher alcohols may similarly
produced, separated, processed, reacted, etc. as desired.
Isolation of Alcohols from Fermentation
When the renewable ethanol and isobutanol are prepared by
fermentation, the ethanol can be removed from the fermentor by
methods known in the art, for example steam stripping,
distillation, pervaporation, etc. (see, e.g., Perry & Chilton,
CHEMICAL ENGINEER'S HANDBOOK, 4.sup.th Ed.).
Isobutanol can also be removed from the fermentor by various
methods, for example fractional distillation, solvent extraction
(e.g., with a renewable solvent such as renewable oligomerized
hydrocarbons, renewable hydrogenated hydrocarbons, renewable
aromatic hydrocarbons, etc. prepared as described herein), gas
stripping, adsorption, pervaporation, etc., or by combinations of
such methods, prior to dehydration. In certain embodiments, ethanol
and butanol are removed from the fermentor in the vapor phase under
reduced pressure (e.g., as an azeotrope with water as described in
U.S. Pat. Appl. Pub. No. 2009/0171129). In some such embodiments,
the fermentor itself is operated under reduced pressure without the
application of additional heat (other than that used to provide
optimal fermentation conditions for the microorganism) and without
the use of distillation equipment, and the produced isobutanol is
removed as an aqueous vapor (or azeotrope) from the fermentor. In
other such embodiments, the fermentor is operated under
approximately atmospheric pressure or slightly elevated pressure
(e.g., due to the evolution of gases such as CO.sub.2 during
fermentation) and a portion of the feedstock containing the
isobutanol is continuously recycled through a flash tank operated
under reduced pressure, whereby the isobutanol is removed from the
headspace of the flash tank as an aqueous vapor or water azeotrope.
These latter embodiments have the advantage of providing for
separation of the isobutanol without the use of energy intensive or
equipment intensive unit operations (e.g., distillation), as well
as continuously removing a metabolic by-product of the
fermentation, thereby improving the productivity of the
fermentation process. The resulting wet isobutanol can be dried and
then dehydrated, or dehydrated wet (as described herein), then
subsequently dried.
The production of renewable isobutanol by fermentation of
carbohydrates typically co-produces small (<5% w/w) amounts of
3-methyl-1-butanol and 2-methyl-1-butanol and much lower levels of
other fusel alcohols. One mechanism by which these by-products form
is the use of intermediates in hydrophobic amino acid biosynthesis
by the isobutanol-producing metabolic pathway that is engineered
into the host microorganism. The genes involved with the production
of intermediates that are converted to 3-methyl-1-butanol and
2-methyl-1-butanol are known and can be manipulated to control the
amount of 3-methyl-1-butanol produced in these fermentations (see,
e.g., Connor and Liao, Appl Environ Microbiol 2008 (74) 5769).
Removal of these genes can decrease 3-methyl-1-butanol and/or
2-methyl-1-butanol production to negligible amounts, while
overexpression of these genes can be tuned to produce any amount of
3-methyl-1-butanol in a typical fermentation. Alternatively, the
thermochemical conversion of biomass to mixed alcohols produces
both isobutanol and these pentanols. Accordingly, when biomass is
converted thermochemically, the relative amounts of these alcohols
can be adjusted using specific catalysts and/or reaction conditions
(e.g., temperature, pressure, etc.).
Dehydration to Ethylene and Butenes
Renewable ethanol and butanols obtained by biochemical or
thermochemical production routes as described herein can be
converted into their corresponding olefins by reacting the alcohols
over a dehydration catalyst under appropriate conditions (see e.g.
FIG. 1). Typical dehydration catalysts that convert alcohols such
as ethanol and isobutanol into ethylene and butene(s) include
various acid treated and untreated alumina (e.g., .gamma.-alumina)
and silica catalysts and clays including zeolites (e.g.,
.beta.-type zeolites, ZSM-5 or Y-type zeolites, fluoride-treated
.beta.-zeolite catalysts, fluoride-treated clay catalysts, etc.),
sulfonic acid resins (e.g., sulfonated styrenic resins such as
Amberlyst.RTM. 15), strong acids such as phosphoric acid and
sulfuric acid, Lewis acids such boron trifluoride and aluminum
trichloride, and many different types of metal salts including
metal oxides (e.g., zirconium oxide or titanium dioxide) and metal
chlorides (e.g., Latshaw BE, Dehydration of Isobutanol to
Isobutylene in a Slurry Reactor, Department of Energy Topical
Report, February 1994).
Dehydration reactions can be carried out in both gas and liquid
phases with both heterogeneous and homogeneous catalyst systems in
many different reactor configurations (see, e.g., FIG. 2).
Typically, the catalysts used are stable to the water that is
generated by the reaction. The water is usually removed from the
reaction zone with the product. The resulting alkene(s) either exit
the reactor in the gas or liquid phase, depending upon the reactor
conditions, and may separated and/or purified downstream or further
converted in the reactor to other compounds (e.g., isomers, dimers,
trimers, etc.) as described herein. The water generated by the
dehydration reaction may exit the reactor with unreacted alcohol
and alkene product(s) and may be separated by distillation or phase
separation. Because water is generated in large quantities in the
dehydration step, the dehydration catalysts used are generally
tolerant to water and a process for removing the water from
substrate and product may be part of any process that contains a
dehydration step. For this reason, it is possible to use wet (e.g.,
up to about 95% or 98% water by weight) alcohol as a substrate for
a dehydration reaction, then remove water introduced with alcohol
in the reactor feed stream with the water generated by the
dehydration reaction during or after the dehydration reaction
(e.g., using a zeolite catalyst such as those described U.S. Pat.
Nos. 4,698,452 and 4,873,392). Additionally, neutral alumina and
zeolites can dehydrate alcohols to alkenes but generally at higher
temperatures and pressures than the acidic versions of these
catalysts. In certain embodiments, the alkene(s) produced in the
dehydration reaction are isolated after the dehydration step,
before being used as feedstocks for subsequent process steps (e.g.,
oligomerization, dehydrogenation, disproportionation, etc.).
Depending on the particular configuration of the process, isolation
of the alkenes after formation in the dehydration reactor can offer
certain advantages, for example when the dehydration is carried out
in the gas phase, while subsequent process steps are carried out in
the liquid phase. However, in certain other embodiments of the
process of the present invention, the alkenes can be used directly
from the product stream of the dehydration reactor, without
isolation (e.g., when the dehydration and the subsequent process
steps are carried out under similar temperature and pressure
conditions and/or when such subsequent steps are relatively
insensitive to water).
Renewable ethylene may be produced directly by the dehydration of
renewable ethanol. However, when 1-butanol, 2-butanol, or
isobutanol are dehydrated, a mixture of four C.sub.4
olefins--1-butene, cis-2-butene, trans-2-butene, and isobutene--can
be formed. The exact concentration in a product stream of each
butene isomer is determined by the thermodynamics of formation of
each isomer. Accordingly, the reaction conditions and catalysts
used can be manipulated to affect the distribution of butene
isomers in the product stream. Thus, one can obtain butene mixtures
enriched in a particular isomer. However, production of a single
butene isomer by dehydration is generally difficult. For example,
dehydration of isobutanol at 280.degree. C. over a .gamma.-alumina
catalyst can be optimized to produce up to 97% isobutene despite an
expected equilibrium concentration of .about.57% at that
temperature (see FIG. 3). However, there is currently no known
method for cleanly dehydrating isobutanol to 99+% isobutene (Saad L
and Riad M, J Serbian Chem Soc 2008 (73) 997).
The dehydration conditions for isobutanol can be varied in the
process of the present invention to provide different butene isomer
compositions suitable for producing a desired product mixture. For
example, if it is desirable to increase the level of propylene
produced by the present process (e.g., by disproportionation of
ethylene and 2-butene, as described herein), isobutanol dehydration
reaction conditions can be adjusted (e.g., reactor temperature,
pressure, residence time, catalyst identity, etc.) to increase the
relative amounts of 2-butene in the dehydration product stream.
Alternatively, the dehydration reaction can be combined in various
ways with an isomerization reaction (using suitable catalysts and
conditions as described herein) to effectively achieve a desired
butene isomer distribution. For example, if increased amounts of
2-butene are desired, the 1-butene and isobutene isomers can be
recycled one or more times at various stages in the process (e.g.,
after dehydration of isobutanol, and/or after any other unit
operations utilizing a feedstock containing 1-butene or isobutene)
to an isomerization reaction to produce additional 2-butene,
thereby effectively increasing the amount of 2-butene produced.
Propylene by Metathesis
Propylene is conventionally produced by cracking higher
hydrocarbons, and as a byproduct in other processes in petroleum
refineries. Renewable propylene could be produced by dehydration of
renewable propanols such as isopropanol or n-propanol (e.g. derived
from renewable acetone provided by so-called "ABE" fermentation
processes, or from propanol produced from biomass by thermochemical
processes), but such "ABE" processes are generally relatively
inefficient, and the resulting renewable propanol is accordingly
not cost competitive with petrochemically derived propanol (e.g.,
produced by hydroformylation of petroleum derived ethylene).
However, renewable propylene can be more efficiently produced by
the disproportionation of renewable ethylene and renewable
2-butene. As described herein, ethylene can be readily prepared by
dehydration of ethanol, and 2-butene can be prepared by the
dehydration of isobutanol under suitable conditions, and/or by the
isomerization of renewable isobutene or 1-butene produced by the
dehydration of isobutanol.
The specific unit operations employed in the preparation of
renewable propylene will depend on the nature of the starting
materials and desired ultimate products. For example, renewable
propylene can be prepared by separately dehydrating ethanol and
butanol, followed by disproportionation of at least a portion of
the ethylene and butene(s) produced as described herein (e.g., the
remaining portion of the ethylene and butene(s) used in other unit
operations), or by the dehydration of mixtures of isobutanol and
ethanol to a mixture of ethylene and butylenes, at least a portion
of which is then disproportionated in the presence of the
appropriate metathesis catalyst to provide propylene. Since
dehydration of isobutanol typically produces a mixture of butene
isomers, and optimal conditions for dehydrating isobutanol and
ethanol are typically somewhat different, in various embodiments
the dehydration of isobutanol and ethanol are carried out
separately (e.g., in separate dehydration reactors, or at different
times in the same dehydration reactor). In particular embodiments,
the dehydration of isobutanol and ethanol are carried out in one or
more separate isobutanol dehydration reactors and one or more
separate ethanol dehydration reactors, and the resulting ethylene
and 2-butene are then reacted in one or more metathesis reactors in
the presence of an appropriate metathesis catalyst.
Depending upon the specific mixture of butenes formed after
dehydration of isobutanol, and the value of particular
intermediates or products, a portion of the various butenes can be
subjected to various additional unit operations. For example, a
portion of the unreacted isobutene can be isomerized to linear
butenes (1- and 2-butenes) and the linear butenes (particularly
2-butenes) can be recycled back to the disproportionation step, or
the isobutene can be converted to, e.g., tort-butyl ethers or
ten-butanol by reaction with alcohols or water, oligomerized and
hydrogenated to higher alkanes/alkenes suitable for use in fuels
(e.g., isooctane/isooctene), dehydrocyclized to aromatics (e.g.,
xylenes such as o-xylene, p-xylene or m-xylene), etc. The
isomerization of isobutene can be carried out in a separate
isomerization step (e.g., in a separate isomerization reactor), or
can occur in-situ during the disproportionation reaction by
appropriate selection of catalyst in the metathesis reactor.
In some embodiments, renewable propylene is prepared using a method
similar to that described in U.S. Pat. No. 7,214,841, in which
renewable butenes (e.g., a mixture comprising 1-butene, 2-butenes,
and/or isobutene) and renewable ethylene, prepared as described
herein, are reacted in the presence of a metathesis catalyst. Since
isobutene may also react with renewable 1- or 2-butenes in the
presence of a metathesis catalyst (producing, e.g., mixed pentenes
and hexenes), in various embodiments isobutene is removed from the
butene mixture prior to the metathesis step to minimize formation
of pentenes and hexenes. However, pentenes and hexenes are easily
separated from ethylene and propylene, and can be used as chemical
intermediates for further unit operations in the process of the
present invention, or as fuel blend stocks, etc. Accordingly, in
some embodiments the isobutene is not removed from the metathesis
reaction feedstock, and the resulting pentenes and hexenes are
subsequently removed and utilized as described herein, while
ethylene can be recycled to the metathesis reaction as feedstock
(and the propylene can be recovered). Any isobutene remaining in
the metathesis product mixture can be removed and recycled to a
separate rearrangement step (e.g., to produce linear butenes) or
diverted to other processes (e.g., oligomerization, oxidation, etc.
to produce biofuels, acrylates, aromatics, etc.) as described
herein.
In various embodiments, renewable propylene is formed by reacting
an approximately 1.3:1 molar mixture of renewable ethylene and
renewable 2-butene in a metathesis reactor in the presence of a
suitable metathesis catalyst as described herein. The approximately
1.3:1 molar mixture of renewable ethylene and renewable 2-butene
can be formed by mixing a suitable portion of the renewable
ethylene formed by dehydration of renewable ethanol and a portion
of the renewable 2-butene isolated from the mixture of butene
isomers formed by dehydration of renewable isobutanol. The
renewable 2-butene can be obtained by separation from the mixture
of butene isomers formed after dehydration of isobutanol, using
suitable methods such as fractional distillation, absorption, etc.
In other embodiments, the molar ratio of renewable ethylene and
renewable 2-butene can be adjusted depending on the composition of
the metathesis feedstock stream(s) and/or the metathesis reaction
conditions (e.g., temperature, pressure, residence time, etc.) to
maximize production of a desired metathesis product (e.g.,
propylene) or to adjust the composition of the product stream for
subsequent unit operations. For example, when the feedstock
comprises a mixture of propylene, isobutene, and linear butenes, it
may be desirable to increase the molar ratio of 2-butenes in the
feedstock to compensate for side-reactions which can reduce the
amount of 2-butenes available for reaction with ethylene (e.g., to
maximize propylene production). Alternatively, if metathesis
conditions (e.g., addition of an isomerization catalyst such as
magnesium oxide) are selected which promote isomerization of
1-butenes and/or isobutene to 2-butenes in the metathesis reactor,
the feedstock can comprise lower levels of 2-butenes, so that
optimal levels of 2-butenes are provided by 2-butene initially
present in the feedstock and 2-butenes produced in-situ in the
metathesis reaction by isomerization of isobutene and/or
1-butene.
In still other embodiments, the mixed butenes can be oligomerized
over an acidic ion exchange resin under conditions which
selectively convert isobutene to isooctene (e.g., using the methods
of Kamath et al., Ind Engr Chem Res 2006 (45) 1575-1582), but leave
the linear butenes substantially unreacted, thereby providing a
substantially isobutene-free mixture of linear butenes (e.g.,
containing less than about 10%, 5%, 4%, 3%, 2%, 1% of isobutene, or
any other value or range of values therein or therebelow). After
separation of isooctene from the mixed linear butenes, the
substantially isobutene-free renewable linear butenes can then be
combined with renewable ethylene and reacted in the presence of a
metathesis catalyst to form renewable propylene.
The disproportionation/metathesis of ethylene and linear butenes
(e.g., 1- and/or 2-butene) can be carried out in the presence of
one or more suitable metathesis catalysts, optionally including one
or more components which may catalyze the rearrangement of
isobutene to linear butenes (particularly 2-butenes) as described
herein. A non-limiting list of suitable metathesis catalysts
include, for example, oxides, hydroxides, or sulfides of metals
such as tungsten, molybdenum, rhenium, niobium, tantalum, vanadium,
ruthenium, rhodium, iridium, iron, potassium, chromium, and osmium.
These metal oxides/hydroxides/sulfides can be supported on a high
surface-area (e.g., 10 m.sup.2/g or more) inorganic carrier known
in the catalyst art, such as silica, .gamma.-alumina, titania, etc.
The metathesis catalyst can also contain a promoter compound to
increase catalyst activity and/or specificity, such as lithium,
sodium, potassium, cesium, magnesium, calcium, strontium, barium,
zinc, yttrium compounds (e.g., elemental forms as well as oxides,
hydroxides, nitrates, acetates, etc., as described in Banks R L and
Kukes S G, J Molec Cat 1985 (28) 117-1311; U.S. Pat. Pub. No.
2008/0312485; and U.S. Pat. Nos. 4,575,575, and 4,754,098), or an
inorganic compound containing a promoter, such as hydrotalcite, or
in particular embodiments, tungsten oxide on silica and magnesium
oxide (e.g., as described in U.S. Pat. No. 7,214,841). In other
embodiments, the renewable linear butenes (produced as described
herein by the dehydration of renewable isobutanol) are reacted with
renewable ethylene in the presence of a catalyst comprising rhenium
oxide on alumina.
Suitable metathesis reaction conditions include those described in
U.S. Pat. No. 3,261,879: temperatures ranging from about
250.degree. F. to about 550.degree. F., pressures ranging from
about 0-1500 psig, WHSV values ranging from about 0.5 to 20
hr.sup.-1, a minimum 30% molar excess ethylene (e.g., moles
ethylene at least about 1.3 times moles butenes). Alternatively,
suitable metathesis conditions include those described in U.S. Pat.
Appl. Pub. No. 2008/0312485: a catalyst comprising a mixture of
tungsten oxide on silica and hydrotalcite, reaction temperature of
about 200.degree. C., and a reaction pressure of about 3.5 MPa.
In most embodiments, the renewable butenes and ethylene in the
metathesis feedstock are purified to remove impurities which may
"poison" the metathesis catalyst. For example, purification may
include removing water; oxygenates such as carbon dioxide,
alcohols, aldehydes, acids, etc.; nitrogen or nitrogen-containing
compounds; sulfur-containing compounds such as hydrogen sulfide,
ethyl sulfide, diethyl sulfide, methyl ethylsulfide; alkynes such
as acetylene and methylacetylene; dienes such as butadiene, etc. in
some embodiments, purification may include removing isobutene (as
described herein). In various embodiments, the levels of such
impurities in the metathesis feedstock are maintained below about
10 ppm, in most embodiments less than 1 ppm. Purification can be
carried out using conventional methods, for example the methods
described in U.S. Pat. Nos. 3,261,875 and 7,214,841, or U.S. Pat.
Appl. Pub. No. 2008/0312485, in which the metathesis feedstock is
passed over an absorbent bed comprising alumina, zeolites,
magnesium and other metal oxides. In most embodiments, a "poisoned"
metathesis catalyst can be regenerated in air at about
>1000.degree. F. In particular embodiments the metathesis
catalyst is periodically regenerated by heating the catalyst in the
presence of oxygen (e.g., air) as described herein. For example,
the process of the present invention can employ two or more
metathesis reactors such that at least one of the metathesis
reactors can be regenerated while the other metathesis reactors are
in operation, thereby permitting continuous operation of the
process.
Isobutene and Linear Butenes
As described herein, the dehydration of isobutanol typically
provides a mixture of butene isomers, including isobutene and
linear butenes. Depending upon the dehydration conditions used, the
mixture of butenes in an isobutanol dehydration product stream can
contain varying amounts of isobutene. For example, if the
dehydration is carried out at lower temperatures, typically a
higher percentage of the butene product stream comprises isobutene
(see FIG. 3). Accordingly, if higher levels of isobutene production
are desirable (e.g., for the production of polyisobutylene, butyl
rubber, other butene copolymers, xylenes, etc.), the process
conditions of the isobutanol dehydration can be adjusted to
increase the percentage of isobutene produced in the isobutanol
dehydration product stream. The remaining linear butenes can be
isomerized (e.g., in a separate isomerization reactor) to form
additional isobutene, which can then be combined with the isobutene
produced from dehydration, or diverted to other processes, e.g.,
oligomerization, dehydrogenation, dehydrocyclization, isomerized to
linear butenes for disproportionation with ethylene to form
propylene, etc.
Alternatively, if higher levels of linear butenes are desirable
(e.g., for disproportionation with ethylene to form propylene,
dehydrogenation to form butadiene, etc.), the isobutanol
dehydration process conditions can be adjusted to increase the
proportion of linear butenes formed (e.g., by increasing the
dehydration process temperature), and the isobutene can be
separated from the isobutanol dehydration product stream and
isomerized (e.g., in a separate isomerization reactor) to form
additional linear butenes, which can be combined with the initially
formed linear butenes. Alternatively, if the desired product is
butadiene, the mixture of linear butenes and isobutene can be
dehydrogenated to form a mixture of isobutene and butadiene. Since
isobutene is substantially unreactive to dehydrogenation conditions
for forming butadiene from linear butenes, the isobutene remains
unreacted in the product stream, and can be readily separated from
the butadiene. The unreacted isobutene can then be recycled and
isomerized to form additional linear butenes, or diverted to other
process steps.
Butadiene
Di-olefins (dienes) such as butadiene are conventionally produced
in petrochemical refineries by the cracking reactions that generate
C.sub.4-containing olefin streams for petrochemical use. If
additional di-olefins are required, they can be produced by
dehydrogenation of the C.sub.4 mono-olefins. For example, butadiene
may be produced by passing raffinate-2 over a dehydrogenation
catalyst.
Dehydrogenation catalysts convert saturated carbon-carbon bonds in
organic molecules into unsaturated double bonds (see FIG. 4).
Typical dehydrogenation catalysts include mixtures of metal oxides
with varying degrees of selectivity towards specific olefins. For
example, in certain oxidative dehydrogenations, iron-zinc oxide
mixtures favor 1-butene dehydrogenation while
cobalt-iron-bismuth-molybdenum oxide mixtures favor 2-butene
dehydrogenation (see, e.g., lung et al., Catalysis Letters 2008
(123), 239). Other examples of dehydrogenation catalysts include
vanadium- and chrome-containing catalysts (see, e.g.,
Toledo-Antonio et al., Applied Catalysis A 2002 (234) 137),
ferrite-type catalysts (see, e.g., Lopez Nieto et al., J Catalysis
2000 (189) 147), manganese-oxide doped molecular sieves (see, e.g.,
Krishnan V V and Suib S L, J Catalysis 1999 (184) 305),
copper-molybdenum catalysts (see, e.g., Tiwari et al., J Catalysis
1989 (120) 278), and bismuth-molybdenum-based catalysts (see, e.g.,
Batist et al., J Catalysis 1966 (5) 55).
Dehydrogenation of an olefin to a di- or polyolefin can occur if
the olefin molecule can accommodate one or more additional double
bonds. For example, 1-butene can be dehydrogenated to butadiene
(see FIG. 5). Dehydrogenation catalysts are also capable of
rearranging olefinic bonds in a molecule to accommodate a second
olefin bond, generally when skeletal rearrangement is not required
(e.g., rearrangement by one or more hydrogen shifts), but these
catalysts typically do not catalyze skeletal rearrangements (e.g.,
breaking and reforming C--C bonds) under dehydrogenating
conditions. For example, 2-butene can be dehydrogenated to
butadiene but isobutene is not typically dehydrogenated to
butadiene in the same process unless the reaction
conditions/catalysts are selected to both promote skeletal
rearrangement and dehydrogenation. Alternatively, one or more
process units may be employed, wherein a stream comprising
isobutene may be subject to isomerization conditions to promote the
formation of linear butenes (e.g., as described herein) to effect
skeletal rearrangement, then subsequently subject to
dehydrogenation conditions to maximize production of butadiene form
a mixed butene stream.
Two major types of dehydrogenation reactions are conventionally
used to produce olefins from saturated materials (see, e.g.,
Buyanov R A, Kinetics and Catalysis 2001 (42) 64). A first type,
endothermic dehydrogenation, typically uses a dehydrogenation
catalyst (e.g., chromia-alumina-based, spinel supported
platinum-based, phosphate-based, and iron oxide-based catalysts),
high heat (typically 480-700.degree. C.), and a reactor
configuration (typically fixed-bed and fluidized-bed reactors) that
favors the formation of hydrogen gas to drive the reaction forward,
and also employs dilution of the feedstock with gases such as
helium, nitrogen, or steam to lower the partial pressure of any
hydrogen that is formed in the reaction. Alternatively, the
reaction may be conducted under reduced pressure (e.g., from 0.1 to
0.7 atm) to effect reduction of the partial pressure of hydrogen in
the reaction, promoting the formation of products. In a second type
of hydrogenation, exothermic dehydrogenation, the catalysts
typically function in the absence of oxygen, minimizing the
formation of oxidized products (e.g., methacrolein and
methacrylate, when the feedstock comprises butenes). Oxidative
dehydrogenation typically employs mixed metal oxide-based
dehydrogenation catalysts (typically containing molybdenum,
vanadium, or chromium), lower temperatures (300-500.degree. C.),
and a fixed- or fluidized-bed reactor configuration. The process
may include the addition of oxygen to the reaction to drive the
reaction. Introduced oxygen reacts with produced hydrogen to form
water, thus reducing the partial pressure of hydrogen in the
reactor and favoring the formation of additional products. Both
types of dehydrogenation reactions are applicable to the invention
described herein. In some embodiments wherein hydrogen production
is desired, endothermic dehydrogenation may be used and reactions
conditions may be optimized to maximize hydrogen capture (e.g., for
subsequent use in hydrogenation reactions or unit operation as
described herein).
The selectivity of dehydrogenation catalysts towards olefins that
can accommodate a second olefinic bond can be used to prepare
dienes (e.g., butadiene), or alternatively used as a method of
purifying the olefin mixture (e.g. by facilitating separation of a
diene from unreactive mono-olefins). For example, as described
herein, the dehydration of isobutanol typically produces isobutene
and both 1- and 2-butenes. Treatment of this product mixture with a
dehydrogenation catalyst selectively converts the 1- and
2-butenes--but not isobutene--to butadiene. It is possible that
some skeletal rearrangement of the isobutene occurs during the
dehydrogenation reaction, but this rearranged material generally is
dehydrogenated to form butadiene. After complete dehydrogenation
(which may require recycling unreacted butenes back to the
dehydrogenation feedstock), the butadiene and unreacted isobutene
can be readily separated by extractive distillation of the
butadiene, to produce high purity (about 80-100%, e.g., >about
80%, >about 85%, >about 90%, >about 95%, >about 98%,
>about 99%, or >about 99.8%) isobutene and butadiene streams
suitable e.g. for use as a monomer feedstock for
polymerization.
Renewable linear butenes are readily dehydrogenated to renewable
butadiene. Accordingly, in the process of the present invention, a
portion of the linear butenes produced by dehydration of renewable
isobutene can be dehydrogenated to 1,3-butadiene. Under typical
linear butene dehydrogenation conditions, isobutene is relatively
inert. Accordingly, in various embodiments of the process,
butadiene can be produced by dehydrogenation of mixtures of butenes
containing both linear butenes and isobutene. In some embodiments,
it may be desirable to remove isobutene from the dehydration
product/dehydrogenation feedstock prior to the dehydration reaction
(e.g., such that the dehydration feedstock contains essentially
only linear butenes). When a mixture of linear butenes and
isobutene is dehydrogenated, the dehydrogenation product stream
comprises butadiene, unreacted isobutene, and optionally unreacted
linear butenes (e.g., produced under low conversion conditions). In
some embodiments, at least a portion of the unreacted linear
butenes can be recycled back to the dehydrogenation reactor to
further convert linear butenes to butadiene (thereby increasing the
overall yield of butadiene), and/or a portion of the unreacted
linear butenes can be reacted with at least a portion of the
ethylene to form propylene (as described herein). The unreacted
isobutene can be separated from butadiene, and at least a portion
of the unreacted isobutene can be recycled to a separate
isomerization step (e.g., producing linear butenes as shown in FIG.
6) or portions of the unreacted isobutene can be diverted to other
processes (e.g., oligomerization, oxidation, etc. to produce
biofuels, acrylates, aromatics, etc.) as described herein. If the
unreacted isobutene is isomerized to linear butenes, at least a
portion of these linear butenes can be recycled back to a
dehydrogenation step to produce additional butadiene, or
alternatively diverted to other processes such as
disproportionation with ethylene to produce additional propylene,
alkylation of aromatics, etc.
In still other embodiments, the mixed butenes can be oligomerized
over an acidic ion exchange resin under conditions which
selectively convert isobutene to isooctene (e.g. using the methods
of Kamath R S et al, Industrial Engineering and Chemistry Research
2006, 45, 1575-1582), but leave the linear butenes essentially
unreacted, thereby providing a substantially isobutene-free mixture
of linear butenes (containing e.g., less than about 1% isobutene,
or less than about 0.9%, less than about 0.8%, less than about
0.7%, less than about 0.6%, less than about 0.5%, less than about
0.4%, less than about 0.3%, less than about 0.2%, or less than
about 0.1%, including ranges and subranges thereof). Some or all of
the essentially isobutene-free renewable linear butenes can then be
reacted in the presence of a dehydrogenation catalyst to form
renewable butadiene. In still other embodiments, isobutene can be
removed from a mixed butene stream by, e.g., selective oxidation of
isobutene in the mixed stream to form, e.g., tert-butanol and/or
methyl tert-butyl ether.
In another embodiment, the amount of 1- and 2-butenes produced in
the dehydration of isobutanol can be increased up to the
equilibrium amount accessible at the reaction temperature (see,
e.g., FIG. 3). For example, in some embodiments, dehydration
catalysts are selected such that at 350.degree. C., the dehydration
of isobutanol produces a mixture comprising about 50% isobutene and
about 50% of 1- and 2-butenes. At least a portion of the resulting
mixture can be treated with a dehydrogenation catalyst to produce
butadiene from isobutanol at up to about 50% yield.
In various embodiments the isobutene can be removed from the
mixture of linear butenes prior to dehydrogenation, or
alternatively, if the dehydrogenation conditions and catalyst are
selected to minimize any undesired side reactions of the isobutene,
the isobutene can removed from the product stream after the
dehydrogenation reaction step. In other embodiments, a portion or
all of the isobutene can be diverted to form other valuable
hydrocarbons (e.g., oligomerized to form isooctenes/isooctanes for
biofuels, dehydrocyclized to form aromatics for fuels, phthalates,
etc.). The isobutene can also be rearranged to linear butenes (1-
and 2-butenes), which can then be recycled back to the
dehydrogenation reaction step to form additional butadiene, thereby
increasing the effective yield of butadiene to above 50% relative
to feed isobutanol. If all of the isobutene is recycled, the
effective yield of butadiene in various processes of the present
invention can approach about 100%. However, as some cracking and
"coking" may occur during the dehydrogenation, butadiene yields for
the process of the present invention can be about 90% or more
(e.g., about 95% or more, or about 98% or more, or any other value
or range of values therein or thereabove). The rearrangement of
isobutene can be carried out in a separate isomerization step
(e.g., in a separate isomerization reactor) after removing the
butadiene from the dehydrogenation product, or can be carried out
in-situ during the dehydrogenation reaction by appropriate
selection of catalyst (or by use of a suitable catalyst mixture) in
the dehydrogenation reactor. For example, dehydration catalysts can
be selected which also catalyze rearrangement of isobutene to
linear isobutenes, or the dehydration catalyst can be mixed with an
isomerization catalyst. A few representative acid catalysts
suitable for rearranging isobutene include zeolites such as
CBV-3020, ZSM-5, .beta. Zeolite CP 814C, ZSM-5 CBV 8014, ZSM-5 CBV
5524 G, and YCBV 870; fluorinated alumina; acid-treated silica;
acid-treated silica-alumina; acid-treated titania; acid-treated
zirconia; heteropolyacids supported on zirconia, titania, alumina,
silica; and combinations thereof.
In particular embodiments, the isobutene is substantially removed
from the product stream after the dehydration reaction step in
order to provide a feed stream for the dehydrogenation reaction
step which is substantially free of isobutene (e.g., the butene
component of the dehydrogenation feed stream comprises
substantially only linear butenes). By "substantially removed" we
mean that isobutene has been removed from the indicated feed or
product stream such that after removal, the isobutene in the feed
or product stream comprises less than about 5% (e.g., less than
about 4%, less than about 3%, less than about 2%, or less than
about 1%, or any other value or range of values therein or
therebelow) of the butenes in the indicated feed or product stream.
By "substantially only" in reference to the composition of the
dehydrogenation feed stream, we mean that the linear butenes
comprise at least about 95% (e.g., at least about 96%, at least
about 97%, at least about 98%, at least about 99%, or any other
value or range of values therein or thereabove) of the butenes in
the dehydrogenation feed stream.
In one embodiment, renewable butadiene may be prepared from
renewable isobutanol produced by fermentation as described herein.
The isobutanol thus produced is then dehydrated under conditions
(as described herein) to maximize the yield of linear butenes
(e.g., heterogeneous acidic catalysts such as .gamma.-alumina at
about 350.degree. C.). The resulting mixture of .about.1:1 linear
butenes/isobutene is then contacted with a dehydrogenation catalyst
(e.g., chromium-oxide treated alumina, platinum- and tin-containing
zeolites and alumina, cobalt- and molybdenum-containing alumina,
etc. at about 450-600.degree. C.) to form a mixture of butadiene
and unreacted isobutene. In a specific embodiment, the
dehydrocyclization catalyst is a commercial catalyst comprising
chromium oxide on an alumina support. The remaining isobutene can
then be isomerized to linear butenes as described herein, and
recycled for dehydrogenation in order to produce additional
butadiene (thereby increasing the effective yield of butadiene), or
used as a raw material for other processes or materials as
described herein.
Higher Olefins
C.sub.5 and higher molecular weight olefins can also be prepared by
the process of the present invention from renewable isobutanol
and/or renewable ethanol by various methods, using a variety of
different reactions used individually or in combination. For
example, renewable butenes can be converted to renewable C.sub.5
olefins by, for example by hydroformylation by reacting renewable
butenes (e.g., renewable isobutene) with formaldehyde (which can be
renewable formaldehyde, e.g., prepared from methanol produced from
biomass by thermochemical processes) or CO and H.sub.2, in the
presence of an acidic catalyst (e.g., via the Prins reaction, see
FIG. 6). Renewable pentenes, hexenes and higher molecular weight
olefins and can also be prepared as co-products from the metathesis
of ethylene and butene mixtures as described herein (e.g., by the
disproportionation of isobutene and 1-butene to form ethylene and
methylpentene(s), the disproportionation of 2 equivalents of
isobutene to form dimethylbutene(s), etc.). By varying the relative
amounts of ethylene and the various butene isomers fed to the
metathesis reaction and the metathesis reaction conditions (e.g.,
temperature, pressure, catalyst, residence time, etc., the
metathesis product stream can be accordingly adjusted to provide
desired amounts of ethylene, propylene, butenes, and C.sub.5 and
higher olefins. In particular, higher concentrations of isobutene
and/or 1-butene in the metathesis feedstock would favor higher
levels of C.sub.5 and higher molecular weight olefins.
Renewable C.sub.5 olefins (e.g., isopentene, 3-methyl-1-butene and
2-methyl-2-butene, etc.) can then be converted to, e.g., isoprene
using a dehydrogenation catalyst, under conditions similar to those
used to convert butenes to butadiene as described above.
Alternatively, or in addition to the processes for preparing
olefins described herein, higher molecular weight olefins can be
prepared by oligomerization of lower molecular weight olefins. The
term "oligomerization" or "oligomerizing" refer to processes in
which activated olefins are combined with the assistance of a
catalyst to form larger molecules called oligomers. Oligomerization
refers to the combination of identical olefins with one another
(e.g., ethylene, isobutene, propylene, pentenes, hexenes, etc.) as
well as coupling of different alkenes (e.g., isobutene and
propylene), or the combination of an unsaturated oligomer with an
olefin. For example, isobutene can be oligomerized by an acidic
catalyst to form eight-carbon oligomers (dimers) such as isooctene
(e.g., trimethylpent-1-enes and trimethylpent-2-enes) and/or
twelve-carbon oligomers (trimers) such as
2,2,4,6,6-pentamethylhept-3-ene, 2,4,4,6,6-pentamethylhept-1-ene.
Similarly, oligomers of other monomers can produce higher molecular
weight oligomers. In other embodiments, controlled oligomerization
of propylene can produce dimers (e.g., hexenes), trimers (e.g.,
nonenes), etc. Similarly, pentenes, hexenes, or other monomers may
be combined in a controlled fashion to provide oligomers having a
desired number of carbon atoms. Furthermore, mixed cross-coupling
or oligomerization is also possible. For example, propylene and
butenes may be oligomerized to provide, e.g., heptenes, decenes,
etc.
Heterogeneous or homogenous oligomerization catalysts can be used
in the process of the present invention (see, e.g., G. Busca, "Acid
Catalysts in Industrial Hydrocarbon Chemistry" Chem Rev 2007 (107)
5366-5410. Of the many methods for oligomerizing alkenes, the most
relevant processes for the production of fuels and fine chemicals
generally employ acidic solid phase catalysts such as alumina and
zeolites (see, e.g., U.S. Pat. Nos. 3,997,621; 4,663,406;
4,612,406; 4,864,068; and 5,962,604).
Various methods can be used for controlling the molecular weight
distribution of the resulting oligomers, including methods which
form primarily dimers including isooctene (see, e.g., U.S. Pat. No.
6,689,927), trimers (see, e.g., PCT Pat. Appl. Pub. No. WO
2007/091862), and tetramers and pentamers (see, e.g., U.S. Pat. No.
6,239,321). Typical methods for controlling oligomer molecular
weight include the addition of alcohols such as t-butanol and
diluents such as paraffins. Additionally, higher molecular weight
oligomers and polymers can be formed using similar catalysts
reacting under different conditions. For example, low molecular
weight polyisobutylene (up to 20,000 Daltons) can be produced using
a boron trifluoride complex catalyst (see, e.g. U.S. Pat. No.
5,962,604).
If a mixture of different olefins produced in any of the processes
described herein is oligomerized, the resulting oligomer mixture
comprises the corresponding addition products formed by the
addition of two or more olefins, which can be the same or
different. For example if a mixture of propene and butenes is
oligomerized, the product can comprise "binary" or "dimer" addition
products such as hexenes, heptenes, octenes; "ternary" or "trimer"
addition products such as nonenes, decenes, undecenes, dodecenes,
etc.
The renewable unsaturated aliphatic compounds prepared by
oligomerization in the process of the present invention generally
have, on average, one carbon-carbon double bond per molecule.
However, by selecting appropriate reaction conditions (e.g.,
catalyst identity, residence time, temperature, pressure, etc.),
the oligomers formed can have two or more carbon-carbon double
bonds, e.g., via dehydrodimerization. On average, the product of
the oligomerizing step of the process of the present invention has
less than about two double bonds per molecule. In some embodiments,
the product oligomer has less than about 1.5 double bonds per
molecule. In most embodiments, the unsaturated aliphatic compounds
(alkenes) have on average one double bond. Any of the olefins
produced by the process of the present invention can be converted
to other compounds, for example hydrogenated to form the
corresponding saturated hydrocarbons, oxidized to the corresponding
alcohol, aldehyde, carboxylic acid, homologated with heteroatoms,
etc. using methods known in the art for transforming carbon-carbon
double bonds to other functional groups.
The term "oligomerization" can also include reactions of olefins
with aromatic hydrocarbons in the presence of an oligomerization
catalyst (also termed "alkylation"). Catalysts specifically
intended or optimized for the alkylation of aromatics are also
termed alkylation or alkylating catalysts, and catalysts
specifically intended or optimized for oligomerization of alkenes
are termed oligomerization catalysts. Oligomerization and
alkylation can, in some embodiments, be carried out simultaneously
in the presence of a single catalyst capable of catalyzing both
reactions, or in other embodiments, can be carried out as separate
reactions using separate oligomerization and alkylation catalysts.
For example, benzene can be reacted with isobutylene in the
presence of an oligomerization catalyst as described herein to form
t-butylbenzene or di-t-butylbenzenes. Similarly, toluene can be
reacted in the presence of an oligomerization catalyst and
isobutylene to form t-butylmethylbenzenes, etc.
The alkylation of aromatics can be carried out using industrially
available catalysts such as mineral acids (e.g., phosphoric acid)
and Friedel-Crafts catalysts (e.g., AlCl.sub.3-HCl), for example,
to alkylate renewable benzene (prepared as described herein) with
renewable ethylene or renewable propylene to produce renewable
ethyl benzene and cumene, respectively. Renewable ethyl benzene and
cumene can then be used as starting materials for the production of
renewable phenol and renewable styrene, e.g., using the methods
described in Catalysis Review 2002, (44) 375. Alternatively, solid
acid catalysts such as zeolite-based catalysts can be used to
catalyze the direct alkylation of renewable benzene with renewable
propylene or ethylene.
For more highly reactive olefins (reactivity typically increases
with increasing length of the olefin chain) oligomerization of the
olefin can compete with alkylation of the aromatic, and thus in
some embodiments, high aromatic to olefin ratios may be used to
minimize formation of olefin oligomers (where such oligomers are
undesired) and favor production of alkylated aromatics. Renewable
benzene, toluene and xylene can be alkylated with renewable
propylene or isobutylene to produce heavier aromatic compounds that
are suitable for renewable jet fuel (see, e.g., Ind. Eng. Chem.
Res. 2008 (47) 1828).
Furthermore, since aromatic alkylation conditions are typically
similar to oligomerization conditions, both steps can be performed
in one reactor or one reaction zone by reacting a stream of
renewable aromatics with renewable alkenes in the presence of a
suitable catalyst to provide a mixture of olefin oligomers and
alkyl aromatics suitable for use in transportation fuels (e.g.,
"Jet A" type fuel). Under excess olefin conditions (e.g., low
aromatic/olefin ratios), both aromatic alkylation and
oligomerization will take place. Alternatively, it is well known
that alcohols can also act as alkylating agents under acid
catalytic conditions. Accordingly, in other embodiments, aromatics
can be alkylated with renewable ethanol or renewable isobutanol
under excess alcohol conditions (e.g., dehydration of the alcohol
and subsequent oligomerization occur in the presence of aromatics,
resulting in alkylation of aromatics). In still other embodiments,
oligomerization/aromatic alkylation with propylene or butenes and
one or more aromatics can be carried in the presence of an acid
catalyst in one reaction zone or in one reactor having two or more
reaction zones. In particular embodiments, ethanol or isobutanol
can be used as alkylating agents for aromatics in the presence of
an acid catalyst in one reaction zone.
Aromatics
Renewable aromatic compounds can be produced from renewable
alcohols and olefins, for example, using the methods described in
U.S. Pat. Nos. 3,830,866, 3,830,866, and 6,600,081. In particular,
renewable aromatics can be readily produced from renewable olefins
by dehydrocyclization. For example, renewable propylene dimers
(C.sub.6 olefins) produced as described herein can dehydrocyclized
to form renewable benzene. Similarly; renewable butene dimers
produced as described herein can be dehydrocyclized to C.sub.8
aromatics such as xylenes (particularly p-xylene as described in
U.S. Ser. No. 12/899,285) and ethylbenzene. Since olefins are more
reactive than the primarily saturated alkanes traditionally used in
petroleum refineries to produce aromatics, milder reaction
conditions can be used in the processes of the present invention,
resulting in improved selectivity for a desired single product
(e.g., p-xylene). Alkyl substituted aromatics can alternatively be
prepared by alkylation of unsubstituted or substituted aromatics
(e.g., benzene or toluene) with low molecular weight olefins (e.g.,
ethylene) using an appropriate alkylation catalyst.
In the present integrated process(es), the selectivity for p-xylene
in an aromatic fraction relative to other aromatic products can be
greater than about 90% (e.g., greater than about 95%, greater than
about 98%, or any other value or range of values therein or
thereabove), using, for example, renewable isooctene as a starting
material. The resulting product contains only negligible amounts of
renewable benzene and toluene, and predominately comprises
xylene(s), from which renewable p-xylene can be recovered at very
high purity (e.g., greater than about 90%, greater than about 95%,
greater than about 98%, or any other value or range of values
therein or thereabove). As previously described herein, appropriate
conditions (e.g., catalyst identity, temperature, pressure,
residence time, etc.) may be selected to favor formation of, e.g.,
p-xylene over other xylene isomers.
In alternative embodiments of the process of the present invention,
renewable aromatics--benzene, toluene, and xylene (BTX)--may be
produced by the dehydrocyclodimerization and dehydration of
renewable alkanes, e.g. isobutane, prepared from renewable
alcohols, e.g. isobutanol, reacted with a hydrotreating catalyst.
The hydrodeoxygenation process can be carried out over, e.g.,
Co/Mo, Ni/Mo or both catalysts in the presence of hydrogen at
moderate temperatures (e.g., .about.150.degree. C.). When
isobutanol is used as a starting material in this reaction, the
reaction may be highly selective (.about.90%) for isobutane with
high (e.g., more than 95%) conversion.
The renewable alkenes, e.g., propylene or isobutylene, formed by
the process of the present invention can also be aromatized using
various catalysts, for example zeolite catalysts, e.g. H-ZSM-5
(Ind. Eng. Chem. Process Des. Dev. 1986 (25) 151) or GaH-ZSM-5
(Applied Catalysis 1988 (43) 155), which sequentially oligomerize
the feed olefins, cyclize the oligomerized olefins to naphthenes,
and dehydrate the naphthenes to the corresponding aromatic
compounds. Alternatively, a metal oxide catalyst can be used in
presence of molecular oxygen. This latter type of catalyst
dimerizes the olefin to the corresponding diene, which is further
cyclized to the corresponding aromatic compound. Because such
aromatization conditions are more severe than oligomerization
conditions, these two processes are generally carried out as
separate process steps.
In some embodiments, the production of renewable aromatics from
renewable propylene or isobutylene is achieved according to one of
the following processes:
Aromatization of light olefins using zeolites, e.g. H-ZSM-5 or
GaH-ZSM-5: C.sub.3.fwdarw.C.sub.6-C.sub.8 Aromatics
C.sub.4.fwdarw.C.sub.6-C.sub.8 Aromatics
Oxidative dehydrodimerization of light olefins using metal
oxide/O.sub.2:
2C.sub.3H.sub.6.fwdarw.C.sub.6H.sub.10.fwdarw.benzene+H.sub.2O
2C.sub.4H.sub.8.fwdarw.C.sub.8H.sub.14.fwdarw.p-xylene+H.sub.2O
Dimerization of isobutylene to isooctene followed by its
aromatization using eta-alumina doped with Cr, Zr, and other
elements:
2i-C.sub.4H.sub.8.fwdarw.i-C.sub.8H.sub.16.fwdarw.p-xylene+3H.sub.2
In most embodiments, however, it is desirable to dehydrocyclize
under reducing conditions in order to produce hydrogen as a
co-product. The hydrogen produced in the dehydrocyclization
reaction can then be used to reduce olefins, particularly isooctene
or trimethylheptenes, to the corresponding saturated hydrocarbons
which are useful as transportation fuels or fuel additives.
Hydrogenation
Many hydrogenation catalysts are effective, including (without
limitation) those containing as the principal component iridium,
palladium, rhodium, nickel, ruthenium, platinum, rhenium, compounds
thereof, combinations thereof, and the supported versions
thereof.
When the hydrogenation catalyst is a metal, the metal catalyst may
be a supported or an unsupported catalyst. A supported catalyst is
one in which the active catalyst agent is deposited on a support
material e.g. by spraying, soaking or physical mixing, followed by
drying, calcination, and if necessary, activation through methods
such as reduction or oxidation. Materials frequently used as
supports are porous solids with high total surface areas (external
and internal) which can provide high concentrations of active sites
per unit weight of catalyst. The catalyst support may enhance the
function of the catalyst agent; and supported catalysts are
generally preferred because the active metal catalyst is used more
efficiently. A catalyst which is not supported on a catalyst
support material is an unsupported catalyst.
The catalyst support can be any solid, inert substance including,
but not limited to, oxides such as silica, alumina, titania,
calcium carbonate, barium sulfate, and carbons. The catalyst
support can be in the form of powder, granules, pellets, or the
like. A preferred support material of the present invention is
selected from the group consisting of carbon, alumina, silica,
silica-alumina, titania, titania-alumina, titania-silica, barium,
calcium, compounds thereof and combinations thereof. Suitable
supports include carbon, SiO.sub.2, CaCO.sub.3,
BaSO.sub.4TiO.sub.2, and Al.sub.2O.sub.3. Moreover, supported
catalytic metals may have the same supporting material or different
supporting materials.
In one embodiment, the support is carbon. Further useful supports
are those, including carbon, that have a surface area greater than
100-200 m.sup.2/g. Other useful supports are those, such as carbon,
that have a surface area of at least 300 m.sup.2/g. Commercially
available carbons which may be used include those sold under the
following trademarks: Bameby & Sutcliffe.TM., Darco.TM.,
Nuchar.TM., Columbia JXN.TM., Columbia LCK.TM., Calgon PCB.TM.,
Calgon BPL.TM., Westvaco.TM., Norit.TM. and Barnaby Cheny NB.TM..
The carbon can also be commercially available carbon such as
Calsicat C, Sibunit C, or Calgon C (commercially available under
the registered trademark Centaur.RTM.).
Particular combinations of catalytic metal and support system
suitable for use in the methods of the present invention include
nickel on carbon, nickel on Al.sub.2O.sub.3, nickel on CaCO.sub.3,
nickel on TiO.sub.2, nickel on BaSO.sub.4, nickel on SiO.sub.2,
platinum on carbon, platinum on Al.sub.2O.sub.3, platinum on
CaCO.sub.3, platinum on TiO.sub.2, platinum on BaSO.sub.4, platinum
on SiO.sub.2, palladium on carbon, palladium on Al.sub.2O.sub.3,
palladium on CaCO.sub.3, palladium on TiO.sub.2, palladium on
BaSO.sub.4, palladium on SiO.sub.2, iridium on carbon, iridium on
Al.sub.2O.sub.3, iridium on SiO.sub.2, iridium on CaCO.sub.3,
iridium on TiO.sub.2, iridium on BaSO.sub.4, rhenium on carbon,
rhenium on Al.sub.2O.sub.3, rhenium on SiO.sub.2, rhenium on
CaCO.sub.3, rhenium on TiO.sub.2, rhenium on BaSO.sub.4, rhodium on
carbon, rhodium on Al.sub.2O.sub.3, rhodium on SiO.sub.2, rhodium
on CaCO.sub.3, rhodium on TiO.sub.2, rhodium on BaSO.sub.4,
ruthenium on carbon, ruthenium on Al.sub.2O.sub.3, ruthenium on
CaCO.sub.3, ruthenium on TiO.sub.2, ruthenium on BaSO.sub.4, and
ruthenium on SiO.sub.2.
Raney metals or sponge metals are one class of catalysts useful for
the present invention. A sponge metal has an extended "skeleton" or
"sponge-like" structure of metal, with dissolved aluminum, and
optionally contains promoters. The sponge metals may also contain
surface hydrous oxides, absorbed hydrous radicals, and hydrogen
bubbles in pores. Sponge metal catalysts can be made by the process
described in U.S. Pat. No. 1,628,190, the disclosure of which is
incorporated herein by reference.
In various embodiments, the sponge metals include nickel, cobalt,
iron, ruthenium, rhodium, iridium, palladium, and platinum. Sponge
nickel or sponge cobalt are particularly useful as catalysts. The
sponge metal may be promoted by one or more promoters selected from
the group consisting of Group IA (lithium, sodium, and potassium),
IB (copper, silver, and gold), IVB (titanium and zirconium), VB
(vanadium), VIB (chromium, molybdenum, and tungsten), VIIB
(manganese, rhenium), and VIII (iron, cobalt, nickel, ruthenium,
rhodium, palladium, osmium, iridium, and platinum) metals. The
promoter can be used in an amount useful to give desired results.
For example, the amount of promoter may be any amount less than 50%
by weight of the sponge metal, 0 to 10% by weight, 1 to 5% by
weight, or any other value or range of values therein.
Sponge nickel catalysts contain mainly nickel and aluminum. The
aluminum is typically in the form of metallic aluminum, aluminum
oxides, and/or aluminum hydroxides. Small amounts of other metals
may also be present either in their elemental or chemically bonded
form, such as iron and/or chromium, and may be added to the sponge
nickel to increase activity and selectivity for the hydrogenation
of certain groups of compounds. In certain embodiments, chromium
and/or iron promoted sponge nickel is employed as a catalyst.
Sponge cobalt catalysts also contain aluminum and may contain
promoters. In certain embodiments, the promoters are nickel and
chromium, for example in amounts of about 2% by weight based on the
weight of the catalyst. Examples of suitable sponge metal catalysts
include Degussa BLM 112W, W. R. Grace Raney.RTM. 2400, Activated
Metals A-4000.TM., and W. R. Grace Raney.RTM. 2724.
As stated above, useful catalytic metals include component iridium,
palladium, rhodium, nickel, ruthenium, platinum, rhenium; and
useful support materials include carbon, alumina, silica,
silica-alumina, titania, titania-alumina, titania-silica, barium,
calcium, particularly carbon, SiO.sub.2, CaCO.sub.3, BaSO.sub.4 and
Al.sub.2O.sub.3. A supported catalyst may be made from any
combination of the above named metals and support materials. A
supported catalyst may also, however, be made from combinations of
various metals and/or various support materials selected from
subgroup(s) of the foregoing formed by omitting any one or more
members from the whole groups as set forth in the lists above. As a
result, the supported catalyst may in such instance not only be
made from one or more metals and/or support materials selected from
subgroup(s) of any size that may be formed from the whole groups as
set forth in the lists above, but may also be made in the absence
of the members that have been omitted from the whole groups to form
the subgroup(s). The subgroup(s) formed by omitting various members
from the whole groups in the lists above may, moreover, contain any
number of the members of the whole groups such that those members
of the whole groups that are excluded to form the subgroup(s) are
absent from the subgroup(s). For example, it may be desired in
certain instances to run the process in the absence of a catalyst
formed from palladium on carbon.
The optimal amount of the metal in a supported catalyst depends on
many factors such as method of deposition, metal surface area, and
intended reaction conditions, but in many embodiments can vary from
about 0.1 wt % to about 20 wt % of the whole of the supported
catalyst (catalyst weight plus the support weight). In particular
embodiments, the catalytic metal content range is from about 0.1 wt
% to about 10 wt % by weight of the whole of the supported
catalyst. In yet other embodiments, the catalytic metal content
range is from about 1 wt % to about 7 wt % by weight of the whole
of the supported catalyst. Optionally, a metal promoter may be used
with the catalytic metal in the method of the present invention.
Suitable metal promoters include: 1) those elements from groups 1
and 2 of the periodic table; 2) tin, copper, gold, silver, and
combinations thereof; and 3) combinations of group 8 metals of the
periodic table in lesser amounts.
Temperature, solvent, catalyst, pressure and mixing rate are all
parameters that may affect hydrogenation. The relationships among
these parameters may be adjusted to effect the desired conversion,
reaction rate, and selectivity in the reaction of the process.
In one embodiment, the hydrogenation temperature is from about
25.degree. C. to 350.degree. C. (e.g., from about 50.degree. C. to
about 250.degree. C., or any other value or range of values
therein), and in certain embodiments, from about 50.degree. C. to
200.degree. C. The hydrogen pressure can be about 0.1 to about 20
MPa, or about 0.3 to 10 MPa, and in certain embodiments from about
0.3 to about 4 MPa. The reaction may be performed neat or in the
presence of a solvent. Useful solvents include those known in the
art of hydrogenation such as hydrocarbons, ethers, and alcohols
(where the alcohols and ethers, or hydrocarbon solvents can be
renewable). In particular embodiments, alcohols such as lower
alkanols like methanol, ethanol, propanol, butanol, and pentanol
are useful. Selectivities in the range of at least 70% are
attainable in the process of the present invention, for example
selectivities of at least 85%, at least 90%, or any other value or
range of values therein or thereabove. Selectivity is the weight
percent of the converted material that is a saturated hydrocarbon
where the converted material is the portion of the starting
material that participates in the hydrogenation reaction.
Upon completion of the hydrogenation reaction, the resulting
mixture of products may be separated by a conventional method, such
as for example, by distillation, by crystallization, or by
preparative liquid chromatography.
Products
Embodiments of the present invention also relate to renewable
hydrocarbon feedstocks and products produced according to the
integrated processes described herein. Certain exemplary renewable
hydrocarbon feedstocks produced according to the present processes,
and products formed therefrom according to the integrated methods
described herein, are described below.
Ethylene
The renewable ethylene produced by the processes of the present
invention can be used to prepare other hydrocarbons such as
propylene, styrene (e.g., by alkylation of benzene) etc. as
described herein. Alternatively, at least a portion of the ethylene
can be used to prepare other value-added products such as
polyethylene (e.g., polyethylene homopolymers and copolymers,
waxes, etc.); ethylene oxide (which itself can be used to prepare
other products such as polyethylene oxide polymers and copolymers,
ethylene glycol, ethylene oxide-containing specialty chemicals such
as surfactants, detergents, etc.); halogenated hydrocarbons such as
ethylene dichloride, ethylene chloride, ethylene dibromide,
chloroethylene, trichloroethylene, and polymers and copolymers
derived from these halogenated hydrocarbons (e.g. PVC, PVdC, etc.);
propanal (e.g., by hydroformylation) or propylene (e.g. by
metathesis as described herein).
Propylene
The renewable propylene produced by the process of the present
invention can be used to prepare a variety of renewable products
including renewable polypropylene, renewable ethylene propylene
rubbers; renewable propylene oxide and renewable polymers prepared
from renewable propylene oxide such as polypropylene oxide and
polypropylene oxide/polyethylene oxide copolymers, polypropylene
oxide polyols for polyurethanes, etc.; renewable aldehydes and
ketones such as propanal, acetone, butyraldehyde, isobutyraldehyde,
etc.; 2-ethylhexanol and 2-ethylhexanoic acid; aromatics such as
cumene and phenol; monomers such acrylic acid, acrylonitrile, and
adiponitrile (and derivatives thereof such adipic acid,
1,6-diaminohexane), etc.
Renewable polypropylene can be prepared directly from renewable
propylene prepared as described herein using methods and
polymerization catalysts known in the art (for example, catalysts
and methods described by Hansjorg Sinn and Walter Kaminsky,
"Ziegler-Natta Catalysis", Advances in Organometallic Chemistry
1980 (18) 99-148 and U.S. Pat. No. 7,563,836). The resulting
renewable polypropylene can have any suitable tacticity (e.g.,
atactic, isotactic, syndiotactic, eutactic) depending on the nature
of the catalyst used and polymerization conditions. In addition,
renewable propylene prepared as described herein can be
copolymerized with other suitable monomers such as ethylene and/or
other olefins to prepare thermoplastic polymers (e.g.,
thermoplastic elastomers), at least a portion of which may be
renewable. For example, copolymers prepared with the renewable
propylene prepared as described herein can be prepared by the
methods described in U.S. Pat. No. 5,272,236.
Renewable polypropylene is particularly useful as a replacement for
petroleum derived polypropylene, which is used for a wide variety
of products including backing and non-woven fiber sheets used in
diapers, as a component of hot melt adhesives (e.g., co-monomers in
polyolefin hot melt adhesives), as a component of pressure
sensitive adhesives, in extruded/thermoformed/injection molded
products, fibers, blown films, cast films, foams, etc., as
components and/or copolymers in packaging (films, caps and
closures, bottles, containers, etc.), fibers (e.g., nonwoven
sheets, carpet fibers, textiles, tape and strapping, staple fibers,
bulk and continuous filament, etc.), as components of toys,
housewares (e.g., plastic utensils, cups, storage containers,
etc.), packing and insulating foams, automotive components (e.g.,
interior and exterior trim, bumper fascia, etc.), tools (e.g.,
handles, power tool enclosures, knobs, etc.), electronic enclosures
(e.g., mobile phones, TVs, battery cases, etc.), ropes and cables,
wire cladding, pipes, etc.
Alternatively, or in addition, renewable polypropylene prepared as
described herein can be used to prepare other monomers such as
propylene oxide. Renewable propylene oxide can be prepared by a
variety of methods, including oxidation with cumene hydroperoxide
(e.g., as described in EP 1382602 or U.S. Pat. No. 7,273,941) or
oxidation with hydrogen peroxide (e.g. in the presence of a
titanium or vanadium silicalite catalyst as described in U.S. Pat.
No. 7,273,941 or WO 97/47613). Other methods for oxidizing
propylene to propylene oxide known in the art can also be used. The
renewable propylene oxide thus formed can then be polymerized or
copolymerized using conventional methods (e.g., via base-catalyzed
polymerization with a base such as KOH, with a salen cobalt
catalyst, etc., using a monofunctional initiator such as an
alcohol, ethylene glycol, etc., or a polyfunctional initiator such
as glycerol, pentaerythritol, sorbitol, etc.) to provide at least
partially renewable polypropylene oxide or at least partially
renewable polypropylene oxide copolymers (e.g., ethylene
oxide/propylene oxide copolymers).
If cumene hydroperoxide is used as the oxidizing agent to prepare
propylene oxide, the cumene hydroperoxide itself can be prepared
from renewable propylene and integrated into the process of the
present invention as described herein. For example, renewable
cumene hydroperoxide can be prepared by the oxidation of renewable
cumene, which in turn can be prepared from by various combinations
of olefin oligomerization, dehydrocyclization, and/or alkylation
steps as described herein. For example, renewable propylene can be
dimerized, then dehydrocyclized to form renewable benzene, which
can then alkylated with an additional equivalent of renewable
propylene to firm renewable cumene (e.g., as described in U.S. Pat.
No. 2,860,173 and U.S. Pat. No. 4,008,290). Alternatively,
renewable propylene can be trimerized and dehydrocyclized directly
to form renewable cumene (e.g., similar to the methods described in
Ind. Eng. Chem. Process Des. Dev. 1986 (25) 151; Applied Catalysis
1988 (43) 155; or as described in U.S. Pat. No. 3,879,486). The
product renewable cumene can then be oxidized to renewable cumene
hydroperoxide using known methods.
Renewable cumene hydroperoxide can be used as an oxidizing agent to
oxidize renewable propylene to propylene oxide (e.g., as described
in EP 1382602), and/or decomposed to form renewable phenol and
renewable acetone (e.g., using the method described in U.S. Pat.
No. 5,254,751 or U.S. Pat. No. 2,663,735). In some embodiments, the
production of renewable cumene hydroperoxide from renewable
propylene can be integrated with a process for preparing renewable
propylene oxide, renewable phenol, and renewable acetone (e.g., by
preparing renewable cumene by the
oligomerization-cyclodehydrogenation-alkylation of renewable
propylene, then oxidizing the renewable cumene to form renewable
cumene hydroperoxide, then contacting additional renewable
propylene with the renewable cumene hydroperoxide to form renewable
propylene oxide, and decomposing renewable cumene hydroperoxide to
form renewable phenol and renewable acetone), as exemplified in
FIG. 8.
The renewable acetone prepared by the decomposition of renewable
cumene hydroperoxide can then be used, e.g., as a precursor for
methylmethacrylate monomer (via reaction with hydrogen cyanide), a
precursor for bisphenol A (via reaction with phenol, e.g.,
renewable phenol produced in the decomposition of renewable cumene
hydroperoxide), or used directly as a renewable industrial solvent.
In addition to renewable bisphenol A, the renewable phenol produced
by the decomposition of renewable cumene hydroperoxide can be used
as a synthetic intermediate in the preparation of, e.g., aspirin,
herbicides, cosmetics, sunscreens, etc., and/or as a monomer in the
preparation of synthetic resins (phenol/formaldehyde resins such as
Bakelite, etc.).
Renewable propylene prepared by the methods disclosed herein can
also be converted to oxidized monomers such as renewable acrylic
acid, for example by reacting propylene in the vapor phase in the
presence of a solid phase catalyst, such as those disclosed in WO
2009/017074, e.g., a two-stage reaction over two different catalyst
beds: in the first stage, propylene is oxidized to acrolein using a
bismuth molybdate catalyst in a strongly exothermic reaction (at
about 370.degree. C.); in the second stage, the acrolein gas is
further oxidized to acrylic acid in the gas phase over a molybdenum
vanadium oxide catalyst. Alternatively, the renewable propylene can
be converted to acrylic acid using the methods of U.S. Pat. No.
6,281,384 (e.g., using a bismuth molybdate multicomponent metal
oxide catalyst such as
Mo.sub.12CO.sub.3.5Bi.sub.1.1Fe.sub.0.8W.sub.0.5Si.sub.1.4K.sub.0.05O.sub-
.x or a molybdenum vanadate multimetal oxide such as
Mo.sub.12V.sub.4.8Sr.sub.0.5W.sub.2.4Cu.sub.2.2O.sub.x); in the
presence of a mixed metal oxide catalyst, water, and oxygen using
the method of the EP 1201636; or by oxidation in the presence of a
mixed metal oxide catalyst as described in JP 07-053448 or
WO2000/09260. The resulting renewable acrylic acid can then be
polymerized or copolymerized to form renewable polyacrylic acid and
polyacrylic acid copolymers, polymerized and cross-linked to form
superabsorbent gels e.g. for diapers, esterified to form at least
partially renewable acrylic esters (or fully renewable if
esterified with renewable alcohols). The at least partially
renewable acrylic esters can likewise be polymerized or
copolymerized to renewable acrylate ester polymers or
copolymers.
Renewable methacrylates can also be formed from renewable
propylene, for example by oxycarbonylation of renewable propylene,
e.g., using the catalytic process of U.S. Pat. No. 3,907,882 in
which the propylene, CO and O.sub.2 are reacted in the presence of
a rhenium compound prepared from rhenium (V) chloride, aluminum
chloride, lithium chloride, and sodium acetate. Analogously to
renewable acrylic acid as described herein, renewable methacrylic
acid can be esterified and/or polymerized (or copolymerized) to
form an at least partially renewable methacrylic acid (ester)
polymer or copolymer.
Renewable acrylonitrile can be prepared, e.g., by reacting
renewable propylene in the presence of an ammoxidation catalyst
(e.g., a multicomponent metal oxide catalyst comprising Bi, Mo, P,
and/or Fe oxides), oxygen and ammonia, for example as described in
EP 1201636, U.S. Pat. No. 4,230,640, U.S. Pat. No. 4,267,385, U.S.
Pat. No. 3,911,089, and U.S. Pat. No. 5,134,105. The resulting
renewable acrylonitrile can then be polymerized or copolymerized
(e.g., to form renewable polyacrylonitrile).
Renewable acrylonitrile can also be electrochemically dimerized to
form adiponitrile, for example using the methods described in GB
1089707 and U.S. Pat. No. 4,155,818, or catalytically dimerized
using the methods described in U.S. Pat. No. 4,841,087 (e.g.,
wherein 1,4-dicyanobutene is reduced to adiponitrile). The
resulting renewable adiponitrile can be hydrolyzed to form
renewable adipic acid and/or reduced to form renewable
hexamethylene diamine (1,6-diaminohexane). The renewable adipic
acid or renewable hexamethylene diamine can be polymerized
separately with, respectively an appropriate diamine or diacid (or
synthetic equivalents thereof), or polymerized together to form
completely renewable nylon 6,6. Alternatively, the renewable adipic
acid and hexamethylene diamine can be used in the preparation of
other valuable and useful materials such as polyurethanes or
plasticizers, as crosslinking agents (e.g., for epoxy resins),
etc.
The renewable propylene prepared by the integrated methods
described herein can also be converted to renewable acetone or
propanal by oxidation using known methods, or converted to
renewable C.sub.4 aldehydes, alcohols, and/or acids by
hydroformylation, e.g., using the methods of U.S. Pat. No.
3,274,263 or U.S. Pat. No. 2,327,066.
Higher alcohols and acids such as 2-ethylhexanol or 2-ethylhexanoic
acid can also be prepared from renewable propylene using similar
methods, for example by reacting renewable polypropylene, carbon
monoxide, hydrogen and acetic acid (e.g., prepared by oxidation of
renewable ethanol) in the presence of a suitable catalyst (e.g.,
cobalt acetate) using the methods of U.S. Pat. No. 2,691,674.
2-Ethylhexanol acetate can be selectively prepared under such
conditions at temperatures of about 250.degree. C. to about
290.degree. C. at pressures of about 500-1500 atmospheres and
CO/H.sub.2 ratios of 0.75-1.5. The renewable 2-ethylhexanol acetate
can be hydrolyzed to regenerate acetic acid used in the reaction,
and the resulting 2-ethylhexanol can be oxidized to 2-ethylhexanoic
acid using known methods. Alternatively, 2-ethylhexanol can be
prepared by base-catalyzed aldol condensation of n-butyraldehyde
using the method of U.S. Pat. No. 5,144,089. In various
embodiments, renewable C.sub.4 and C.sub.6 aldehydes, alcohols,
acids and acid derivatives (e.g., amides, nitriles, acid chlorides,
esters, etc.) can be prepared from renewable propylene by known
processes such as hydroformylation, and/or base catalyzed aldol
condensation, and/or reduction, and/or oxidation of the appropriate
intermediates as shown in FIG. 9.
The resulting renewable C.sub.4 and C.sub.6 aldehydes, alcohols,
acids and acid derivatives can be used for various applications,
for example in the synthesis of phthalate ester plasticizers
(2-ethylhexanol), industrial solvents (butanols), specialty
chemicals (metal salts of 2-ethylhexanoic acid), etc.
In still other embodiments, renewable ethylene, butenes, propylene
and/or higher olefins produced by the present integrated methods
may be oligomerized, e.g., as described in U.S. Ser. No. 12/327,723
to provide renewable transportation fuels, e.g., gasoline, jet
fuels and/or diesel fuels.
C.sub.4 Oxidized Hydrocarbons
As described above, the process of the present invention provides
isobutanol from biomass or CO.sub.2 by, e.g., fermentation or
thermochemical methods. Renewable isobutanol can be converted to
other butanol isomers by, for example, rearrangement of isobutanol,
and/or can be converted to various butyraldehydes, butyric acids
and/or butyric acid derivatives by appropriate oxidation or
reaction of the corresponding alcohol. However, in some cases (for
example to ensure complete utilization of the renewable propylene)
it may be desirable to convert a certain portion of the renewable
propylene provided by the methods of the present invention to
various renewable C.sub.4 aldehydes, alcohols, and/or acids by
hydroformylation.
Butenes
As discussed herein, renewable isobutene and linear butenes
produced by the process of the present invention can be used as
starting materials to produce higher molecular weight renewable
olefins and alkanes useful as renewable fuels and fuel additives,
or as monomers for the production of polymers and copolymers, such
as polybutene and polyisobutylene suitable for use in a variety of
applications, for example chemical intermediates for the
preparation of engine oil, fuel additives, and greases; an
intermediate in the preparation of dispersants such as polybutenyl
succinic anhydride; as intermediates in the preparation of sealants
and adhesives; modifiers for polymers such as tackifiers for
polyethylene and for adhesive polymers; and in hydrogenated form as
components of cosmetic formulations.
Butadiene
The renewable butadiene thus obtained can then be converted, for
example, to a wide variety of renewable polymers and co-polymers by
most known methods of polymerization and used in a multitude of
commercial applications. As described herein, renewable butadiene
can be polymerized or copolymerized with other monomers (which
themselves may be renewable monomers or monomers obtained from
conventional, non-renewable sources). For example, very low
molecular weight polymers and copolymers of butadiene, called
telomers or liquid polybutadiene, can be prepared by anionic
polymerization using initiators such as n-butyl lithium, often with
co-initiators such as potassium tert-butoxide or tert-amines as
described in U.S. Pat. No. 4,331,823 and U.S. Pat. No. 3,356,754.
These low molecular weight oligomers (e.g., MW 500-3000) can be
used in pressure sensitive adhesives and thermosetting rubber
applications. Butadiene can also be co- and ter-polymerized with
vinyl pyridine and/or other vinyl monomers (e.g. renewable vinyl
monomers) in an emulsion process to form polymers useful in floor
polishes, textile chemicals and formulated rubber compositions for
automobile tires. Butadiene can also be anionically polymerized
with styrene (e.g., renewable styrene) and vinyl pyridine to form
triblock polymers as taught in U.S. Pat. No. 3,891,721 useful for
films and other rubber applications.
Butadiene and styrene can be sequentially, anionically polymerized
in non-polar solvents such as hexane, to form diblock and triblock
polymers, also called SB elastomers, ranging from rigid plastics
with high styrene content to thermoplastic elastomers with high
butadiene content. These polymers are useful for transparent molded
cups, bottles, impact modifiers for brittle plastics, injection
molded toys as well as components in adhesives. Solution
polybutadiene can be prepared from butadiene, also by anionic
polymerization, using initiators such as n-butyl lithium in
non-polar solvents without utilizing a comonomer. These elastomers
are non-crosslinked during the polymerization and can be used as
impact modifiers in high impact polystyrene and bulk polymerized
ABS resins, as well as in adhesives and caulks. Solution
polymerized polybutadiene can also be compounded with other
elastomers and additives before vulcanization and used in
automobile tires. Emulsion (latex) polymerization can also be used
to convert butadiene and optionally, other monomers such a styrene,
methyl methacrylate, acrylic acid, methacrylic acid, acrylonitrile,
and other vinyl monomers, to polymers having both unique chemical
structure and designed physical structure suitable for specific end
use applications.
Emulsion polymerization utilizes water as the continuous phase for
the polymerization, surfactants to stabilize the growing, dispersed
polymer particles and a compound to generate free radicals to
initiate the polymerization. Styrene-butadiene emulsion rubber used
for automobile tires can be made by this process. Renewable vinyl
acids such as acrylic acid and methacrylic acid (as described
herein) can be copolymerized in the styrene butadiene rubber. Low
levels (0.5-3%) of vinyl acids improve the stability of the latex
and can be beneficial in formulated rubber products such as tires,
especially when containing polar fillers. Higher levels of acid in
rubber latexes, often called carboxylated latex, are used
beneficially in paper coating. Latex polymerization is also used to
produce rubber toughened plastics and impact modifiers. Impact
modifiers made by latex polymerization are also called core-shell
modifies because of the structure that is formed while polymerizing
the monomers that comprise the polymer.
MBS resins are made by a sequential emulsion process where
butadiene (B) and styrene (S) are first polymerized to form the
rubber particle core, typically 0.1-0.5 micrometers in diameter,
and then methyl methacrylate (M) is polymerized to form a
chemically grafted shell on the outer surface of the SB rubber
core, for example as taught in U.S. Pat. No. 6,331,580. This impact
modifying material is isolated from the latex and blended with
plastics to improve their toughness. If acrylonitrile (A) is used
in place of the methyl methacrylate, with slight variations in the
process, such as disclosed in U.S. Pat. No. 3,509,237 and U.S. Pat.
No. 4,385,157, emulsion ABS is the product. Each of these
components in ABS (including acrylonitrile) may be renewable,
produced by the methods described herein. ABS is used in injection
molding and extrusion processes to produce toys, automobile parts,
electronic enclosures and house wares. Nitrile rubber is produced
in a similar emulsion polymerization process when butadiene and
acrylonitrile are copolymerized together to produce a polar
elastomer that is very resistant to solvents. Higher butadiene
content in the elastomer provides a softer, more flexible product
while higher acrylonitrile content results in more solvent
resistance. The rubber is isolated from the latex by coagulation
and can be fabricated into gloves, automotive hoses, and gaskets
where its high resistance to solvents is an advantage.
Renewable butadiene prepared by the process described herein can
also be converted to renewable 1,4-butanediol (BDO) and/or
renewable tetrahydrofuran (THF), for example using the process
described in JP 10-237017 and JP 2001002600 (illustrated below in
Scheme 1), in which butadiene is reacted with acetic acid and
oxygen in the presence of a palladium catalyst (liquid phase at
about 70.degree. C. and 70 bar, using a promoter such as Sb, Bi, Se
or Te) to form 1,4-diacetoxy-2-butene, which is then hydrogenated
(liquid phase, at about 50.degree. C. and 50 bar over a
conventional hydrogenation catalyst such as Pd/C) to
1,4-diacetoxybutane. Acidic hydrolysis of the 1,4-diacetoxybutane
(e.g., using an acidic ion exchange resin) provides BDO and THF in
high yield.
##STR00001##
Renewable BDO and THF can be converted to a variety of renewable
products. For example renewable BDO can be reacted with a suitable
diisocyanates to form renewable Lycra.TM. and Spandex.TM. products,
as well as thermoplastic urethane elastomers. Renewable BDO can
also be used to form renewable polybutylene terephthalate by
reacting renewable BDO with terephthalic acid or terephthalate
esters, or can be copolymerized with renewable aliphatic diacids
such as adipic acid or succinic acid to form renewable aliphatic
polyesters such as polybutylene adipate or polybutylene succinate.
In some embodiments the terephthalic acid or terephthalate esters
can be renewable, prepared by oxidation of renewable xylene made,
e.g., by the method described in U.S. Ser. No. 12/327,723 and U.S.
61/295,886. Renewable BDO can also be used to prepare renewable
.gamma.-butyrolactone (GBL), renewable pyrrolidone solvents such as
N-methylpyrrolidinone (NMP), renewable N-vinylpyrrolidinone (NVP),
etc. as illustrated below in Scheme 2:
##STR00002##
Renewable GBL and NMP can be used as solvents, and renewable NVP
can be used in personal care products such as hairspray.
Renewable butadiene prepared by the processes described herein can
also be used to form renewable dodecanedioic acid (DDDA), or
renewable lauryllactam by forming the oxime of the intermediate
cyclododecanone, then rearranging the oxime to lauryllactam (e.g.,
using the method of U.S. Pat. No. 6,649,757). The lauryllactam can
then be polymerized to form renewable nylon-12, as shown below in
Scheme 3:
##STR00003##
Renewable butadiene prepared by the processes described herein can
also be used to prepare renewable chloroprene, which can be
polymerized to provide renewable synthetic rubbers. Renewable
chloroprene can be prepared by chlorinating renewable butadiene
(e.g., free radical, gas phase chlorination with Cl.sub.2 at
250.degree. C. and 1-7 bar to give a mixture of cis and
trans-1,4-DCB as well as 3,4-DCB). At butadiene conversions of
10-25%, the selectivity to this mixture of DCBs can be 85-95%.
3,4-dichloro-1-butene (3,4-DCB) can be dehydrochlorinated to form
chloroprene (e.g., using dilute alkaline catalysts at 85.degree.
C.), as shown below in Scheme 4. The 1,4-DCB by-products can be
isomerized to 3,4-DCB using a copper catalyst. In addition, by
distilling off the 3,4-DCB during the reaction (b.p. 123.degree. C.
vs. 155.degree. C. for the 1,4-isomers), the equilibrium of the
reaction can be shifted to provide a selectivity of 95-98%.
##STR00004##
Renewable butadiene prepared by the processes described herein can
also be used to prepare renewable nylon-6,6 (Scheme 5). For
example, renewable nylon-6,6 can be prepared by reacting renewable
butadiene with HCN in the presence of a zero valent nickel catalyst
to provide adiponitrile. Adiponitrile can be hydrogenated to form
hexamethylenediamine (HMD), and hydrolyzed to form adipic acid. The
HMD and adipic acid can then be polymerized to form nylon-6,6.
##STR00005##
Alternatively, as shown in Scheme 6, renewable adiponitrile can be
hydrocyanated and cyclized to renewable caprolactam (CL), e.g.,
using a doped Raney Ni (using the method of U.S. Pat. No.
5,801,286) and cyclized to CL in the presence of water (using the
method of U.S. Pat. No. 5,693,793). The renewable caprolactam can
then be polymerized to form renewable nylon-6 using methods known
in the art.
##STR00006##
Renewable butadiene prepared by the processes described herein can
also be used to prepare renewable sulfolene and sulfolane using the
method illustrated in Scheme 7:
##STR00007##
Renewable butadiene prepared by the processes described herein can
also be used to prepare renewable styrene, renewable polystyrene,
and renewable styrenic polymers (e.g., renewable SBR rubbers).
Renewable styrene can be prepared, for example by dimerizing
renewable butadiene to form vinylcyclohexene, which can be
dehydrogenated in a stepwise fashion to form ethyl benzene (e.g.,
using the method of WO 2003/070671), then styrene (e.g., using the
method of U.S. Pat. No. 4,229,603). Alternatively, vinylcyclohexene
can be dehydrogenated directly to styrene. The renewable styrene
can be homopolymerized to form renewable polystyrene, copolymerized
with renewable butadiene to form SBR rubber, etc.
Renewable butadiene prepared by the processes described herein can
also be used to prepare renewable ethylidene norbornene (ENB) for
producing completely renewable or partially renewable
ethylene-propylene-diene rubber (depending on whether renewable
ethylene and/or propylene are used). Renewable ethylene can be
prepared by dehydrogenating renewable ethanol (e.g. produced by
fermentation or thermochemical methods), and renewable propylene
can be prepared, for example by the methods described in U.S.
61/155,029. Renewable ENB can be prepared, for example, by reacting
renewable butadiene and dicyclopentadiene in a four-step process.
In the first step, dicyclopentadiene is decoupled to
cyclopentadiene and reacted with renewable butadiene via
Diels-Alder condensation to vinylnorbornene (VNB). This is followed
by distillation to obtain refined VNB, which is catalytically
isomerized (U.S. Pat. No. 4,720,601) to ENB.
Renewable butadiene prepared by the processes described herein can
also be thermally dimerized to form renewable 1,5-cyclooctadiene
(COD) using the methods of, e.g., U.S. Pat. No. 4,396,787.
Renewable COD can be used in the preparation of renewable ethylene
oligomerization catalysts such as Ni(COD).sub.2. Butadiene can also
be dimerized to produce 1-octene and 1-octanol.
In other embodiments, the dehydration of 3-methyl-1-butanol
produces a mixture of methyl butenes and small amounts of other
pentenes which upon treatment with a dehydrogenation catalyst forms
primarily isoprene from methylpentenes (e.g. 2-methyl-1-butene,
2-methyl-2-butene, 3-methyl-1-butene), for example
3-methyl-1-butene, and other pentadienes, such as 1,3-pentadiene,
from other pentenes. The pentadienes are separated from each other
by distillation. Dehydration catalysts and conditions are optimized
to produce varying amounts of specific olefins, and their resulting
di-olefins upon treatment with a dehydrogenation catalyst.
The purification of isobutene as described above produces renewable
isobutene that meets all current industrial specifications and can
be used to manufacture all chemicals and materials currently
produced, e.g., from conventional petroleum-based isobutene. For
example, renewable or partially renewable polyisobutylene, butyl
rubber, methyl methacrylate, isoprene, and other chemicals can be
produced by the methods of the present invention. Renewable
isobutene can also be oxidized under suitable conditions to provide
methacrylic acid and methacrylic acid esters (Scheme 8). Isobutene
can be oxidized over suitable metal oxide catalysts (e.g., using
the methods described in JP 2005-253415) at temperatures of about
300-500.degree. C. to methacrolein (MAL) which is then further
oxidized to methacrylic acid (MMA) (WO 2003053570) at temperatures
of about 350-500.degree. C. The resultant methacrylic acid can be
further esterified to methylmethacrylate. The oxidation of
isobutene to MMA may also be accomplished in a single step (e.g. as
described in WO2003053570).
##STR00008##
An alternative process for the preparation of MMA is by the
oxidative esterification of MAL to MMA (e.g., as described in U.S.
Pat. No. 4,518,796) using catalysts such as
Pd/Pb/Mg--Al.sub.2O.sub.3 (e.g., as described in JP 2006306731) and
Pd.sub.5Bi.sub.2Fe/CaCO.sub.3 (Scheme 9.
##STR00009##
Additionally, all materials currently produced from butadiene such
as synthetic rubbers and nylon can be manufactured from the
renewable butadiene produced by the dehydrogenation of renewable
butenes according to the present invention. For example, butadiene
is used directly as a monomer and co-monomer for the production of
synthetic rubber. It is also converted into "oxidized" monomers
such as 1,4-butanediol, adiponitrile, and adipic acid as described
herein for the production of polyester and nylon materials (e.g.,
adipic acid is produced by the hydrocarboxylation of butadiene in
the presence of a suitable catalyst, CO and water; e.g.,
adiponitrile is produced by the hydrocyanation of butadiene in the
presence of a suitable catalyst). The production of renewable
isoprene from the dehydrogenation of methylbutenes or the
hydroformylation and dehydration of renewable isobutene allows the
preparation of renewable or partially renewable versions of all
chemicals and materials produced from isoprene, especially
synthetic rubber and other polymers.
One of the major industrial uses of isobutene is in the production
of butyl rubber primarily for use in automobile tires. Butyl rubber
is a high performance polymer comprised of high purity isobutene
crosslinked with di-olefins such as butadiene or isoprene (e.g.,
U.S. Pat. No. 2,984,644; Dhaliwal G K, Rubber Chemistry and
Technology 1994 (67) 567). Typically, 1-3% of di-olefin is blended
with isobutene and co-polymerized in the presence of a
polymerization catalyst such as aluminum chloride and other metal
salts.
In some embodiments, renewable isoprene is produced by contacting
3-methyl-1-butanol or 2-methyl-1-butanol with a dehydration
catalyst and a dehydrogenation catalyst, under conditions similar
to those described herein for preparing renewable butadiene. The
renewable isoprene thus formed may then blended with renewable
isobutene, obtained by the methods described above or by
conventional methods such as hydration of isobutylene to t-butanol
and subsequent dehydration to isobutene, to form a renewable
monomer feedstock for the production of renewable butyl rubber.
Petroleum-based isoprene and isobutene can also used with the
renewable isoprene and/or isobutene to produce butyl rubber that is
partially renewable. In addition to blending purified isoprene with
purified isobutene to produce butyl rubber, a renewable blend of
isobutene and isoprene can be produced by contacting a mixture of
isobutanol and 3-methyl-1-butanol (or 2-methyl-1-butanol) with a
dehydration catalyst to form isobutylene and 3-methyl-butenes (or
2-methyl-butenes) and then contacting this olefin mixture with a
dehydrogenation catalyst to form isobutene and isoprene.
By-products such as butadiene and other C.sub.5 olefins and
di-olefins are removed by extractive distillation to give mixtures
containing only isobutene and isoprene. The amount of isoprene in
the mixture can be Controlled by manipulating the
3-methyl-1-butanol producing pathway in the host microorganism or
the appropriate selection of catalyst in the thermochemical
conversion of biomass. In some embodiments, the 3-methyl-1-butanol
(or 2-methyl-1-butanol) concentration is tuned to 1-3% of the
isobutanol produced such that the resulting isobutene/isoprene
mixture can be directly used to produce butyl rubber.
Alternatively, in other embodiments a higher concentration of
3-methyl-1-butanol is produced to form a mixture of isobutene and
isoprene that is then diluted with pure isobutene to optimize butyl
rubber production. The isoprene produced from 3-methyl-1-butanol
(or 2-methyl-1-butanol) containing isobutanol is also separately
removed and blended with isobutene to the appropriate
concentration. Alternatively, the butadiene produced by the
dehydrogenation of 1- and 2-butenes is used as a cross-linking
agent in a butyl rubber product.
In view of the foregoing description, it will be appreciated that
starting from simple renewable ethanol and isobutanol feedstocks,
essentially any product currently derived or produced from
petroleum feedstocks can be produced by the present integrated
processes. Exemplary methods of producing certain renewable mono-
and polyolefins, unsubstituted and substituted aromatics,
derivatives thereof (e.g., acids, esters, acid derivatives,
heterosubstituted compounds, etc.) and polymers and products
therefrom have been described. It will be appreciated that methods
and/or transformation as described herein for one compound are
generally analogous and applicable to other, similar compounds and
that such transformations and products are within the scope of the
present integrated methods.
The present integrated processes will now be further described with
reference to the following, non-limiting examples.
Example 1
Production of Isobutanol from Lignocellulosics
A cellulosic material consisting of 45% cellulose, 25%
hemicellulose, 22% lignin and 8% other materials is pretreated to
yield a slurry of 8% insoluble cellulose with about 4% insoluble
lignin, 1% glucose, 40 g/L xylose, 2 g/L mannose, 2 g/L galactose,
1 g/L arabinose, 5 g/L acetic acid in solution. The slurry is fed
into an agitated saccharification and fermentation vessel and
charged with cellulase enzyme sufficient to hydrolyze 80% of the
cellulose 72 hours. A microorganism known to ferment glucose,
xylose, mannose, galactose and arabinose to isobutanol is added to
the fermentation, and the vessel is agitated for 72 hours.
Isobutanol produced by the fermentation is separated from the
fermentation broth by distillation. The first isobutanol-containing
distillation cut contains 20% w/w isobutanol and 80% w/w water that
condenses to form two phases--a light phase containing 85%
isobutanol and 15% water and a heavy phase containing 8% isobutanol
and 92% water. The light phase is distilled a second time and two
low-water cuts of isobutanol are obtained. One cut is comprised of
99.5% isobutanol and 0.5% water while the second cut is comprised
of 98.8% isobutanol, 1% 3-methyl-1-butanol, and 0.2% water.
Example 2
Dehydration of Isobutanol
Isobutanol obtained in Example 1 was fed through a preheater and to
a fixed-bed tubular reactor packed with a commercial dehydration
catalyst (BASF AL3996). The internal reactor temperature was
maintained at 300.degree. C. and the reactor pressure was
atmospheric. The WHSV of the isobutanol was 6 hf.sup.-1. Primarily
isobutene and water were produced in the reactor and separated in a
gas-liquid separator at 20.degree. C.; the water had 1% of
unreacted isobutanol and conversion was 99.8%. GC-MS of the gas
phase effluent indicated it was 96% isobutene, 2.5% 2-butene (cis
and trans) and 1.5% 1-butene.
Example 3
Dehydration of Isobutanol
Isobutanol obtained in Example 1 is fed through a preheater and to
a fixed-bed tubular reactor packed with a commercial dehydration
catalyst (e.g., an X-type zeolite). The internal reactor
temperature is maintained at 370.degree. C. and the reactor
pressure is atmospheric. The WHSV of the isobutanol is 3 hr.sup.-1.
A mixture of C.sub.4 olefins and water are produced in the reactor
and separated in a gas-liquid separator at 20.degree. C.; the water
has <1% of unreacted isobutanol and conversion is >99.8%.
GC-MS of the gas phase effluent indicates it is 50% isobutene, 40%
2-butene (cis and trans) and 10% 1-butene.
Example 4
Co-Dehydration of Ethanol and Isobutanol
60 g of a commercial .gamma.-alumina dehydration catalyst (BASF
AL-3996) is loaded into a fixed-bed tubular reactor. A feed mixture
is prepared by mixing 250 mL of ethanol with 750 mL of isobutanol.
The feed mixture is pumped through a preheater and onto the
catalyst bed at a feed rate of 2.5 mL/min. The internal reactor
temperature is maintained at 350.degree. C., the pressure was
atmospheric, and the weight hourly space velocity (WHSV) of the
mixed alcohol feed is .about.2/hr. The products are separated in a
gas-liquid separator. The water contains 0.9 wt % ethanol and 0.3
wt % isobutanol indicating conversions of 99% and 99.9%
respectively. The gas-phase effluent is 35% ethylene and 65%
butenes (molar basis). The butenes are found to be 55% isobutene,
13% 1-butene, 12% cis-2-butene, and 20% trans-2-butene.
Example 4A
Dehydration of Dry Isobutanol
Dry isobutanol (<1 wt % water) obtained in Example 1 was fed
through a preheater to a fixed-bed tubular reactor packed with a
commercial .gamma.-alumina dehydration catalyst (BASF AL-3996). The
internal reactor temperature was maintained at 325.degree. C. and
the reactor pressure was atmospheric. The WHSV of the isobutanol
was 5 hr.sup.-1. Primarily isobutene and water were produced in the
reactor, and were separated in a gas-liquid separator at 20.degree.
C.; the water had <1% of unreacted isobutanol and the conversion
was >99.8%. GC-FID analysis of the gas phase effluent indicated
it was 95% isobutene, 3.5% 2-butene (cis and trans) and 1.5%
1-butene.
Example 5
Purification of Isobutene by Dehydrogenation of Butenes
A mixed butene stream from Example 2, containing 96% isobutene,
2.5% 2-butenes (cis and trans), and 1.5% 1-butene is mixed with air
at a relative feed rate of 10:1 butenes:air. The resultant mixture
is 1.9% oxygen and 3.6% linear butenes. The mixture is preheated to
400.degree. C. and fed at a GHSV of 300 hr.sup.-1 to a fixed-bed
tubular reactor loaded with 2 catalyst beds in sequence; the first
contains ZnFe.sub.2O.sub.4 and the second contains
CO.sub.9Fe.sub.3BiMoO.sub.51. The effluent from the reactor is
dried over a molecular sieve column to remove water. Nitrogen and
oxygen are removed by passing the C.sub.4 stream through a
gas-liquid separator at -78.degree. C. (dry ice bath). The C.sub.4
product is analyzed via GC-MS. The composition is found to be 96%
isobutene, 3.9% butadiene, and 0.1% linear butenes. butadiene is
stripped from the gas stream by extraction with acetonitrile. The
resultant stream is 99.9% isobutene and 0.1% linear butenes with
trace butadiene (<0.01%).
Example 6
Purification of Isobutene by Dehydrogenation of Butenes
A mixed butene stream from Example 3, containing 50% isobutene, 40%
2-butenes (cis and trans), and 10% 1-butene is mixed with air at a
relative feed rate of 4:5 butenes:air. The resultant mixture is
11.7% oxygen and 22.2% linear butenes. The mixture is preheated to
400.degree. C. and fed at a GHSV of 300 hr.sup.-1 to a fixed-bed
tubular reactor loaded with 2 catalyst beds in sequence; the first
contains ZnFe.sub.2O.sub.4 and the second contains
CO.sub.9Fe.sub.3BiMoO.sub.51. The effluent from the reactor is
dried over a molecular sieve column to remove water. Nitrogen and
oxygen are removed by passing the C.sub.4 stream through a
gas-liquid separator at -78.degree. C. (dry ice bath). The C.sub.4
product is analyzed via GC-MS. The composition is found to be 50%
isobutene, 49.9% butadiene, and 0.1% linear butenes. butadiene is
stripped from the gas stream by extraction with acetonitrile. The
resultant stream is 99.9% isobutene and 0.1% linear butenes with
trace butadiene (<0.01%).
Example 7
Preparation of Butadiene from Butenes
120 sccm of nitrogen and 120 sccm of 2-butene (mixture of cis and
trans) was fed through a preheater and to a fixed-bed tubular
reactor packed with 15 g of a commercial Cr.sub.2O.sub.3 on alumina
dehydrogenation catalyst (BASF Snap catalyst). The internal reactor
temperature was maintained at 600.degree. C. and the reactor
pressure was atmospheric. The WHSV of the 2-butene was about 1 hf'.
GC-FID of the gas phase effluent indicated it was 74% linear
butenes (mixture of 1-, cis-2-, and trans-2-), 16% butadiene, 2.5%
n-butane, and 7.5% C.sub.1-C.sub.3 hydrocarbons. The resulting
conversion of 2-butene was 26% (ignoring rearrangement to 1-butene)
with a selectivity to butadiene of 61.5% based on % carbon.
Example 9
Integrated Preparation of Butadiene from Isobutanol
Renewable wet isobutanol (containing 15% water and .about.4%
ethanol) obtained from fermentation was fed through a preheater and
to a fixed-bed tubular reactor packed with a commercial
.gamma.-alumina dehydration catalyst (BASF Snap catalyst). The
internal reactor temperature was maintained at 400.degree. C. and
the reactor pressure was atmospheric. The WHSV of the isobutanol
was .about.0.1 hr.sup.-1. The products were separated in a
gas-liquid separator at 20.degree. C., where relatively pure water
was removed as the liquid product. The gas phase product was dried
over a molecular sieve bed. GC-FID of the gas phase effluent from
the dehydration reactor was 82% isobutylene, 13% linear butenes
(mixture of 1-butene, and cis- and trans-2-butene), 4.5% ethylene,
and 0.5% propylene. The flow of the gas-phase stream was .about.120
sccm. This stream was combined with 120 sccm of nitrogen and was
fed through a preheater and to a fixed-bed tubular reactor packed
with 15 g of a commercial Cr.sub.2O.sub.3 on alumina
dehydrogenation catalyst. The internal reactor temperature was
maintained at 600.degree. C. and the reactor pressure was
atmospheric. The WHSV of the mixed butene stream was about 1
hr.sup.-1. GC-FID of the gas phase effluent indicated it was 78.5%
isobutylene with 2.5% isobutane, 7.5% linear butenes, 3.7% ethylene
with 0.6% ethane, 2.9% butadiene, and the remaining 4.4% was
methane and propylene. This indicates an approximate yield of 22%
butadiene based on linear butenes fed to the dehydrogenation
reactor.
Example 10
Preparation of Propylene from Ethylene and 2-Butenes
A metathesis catalyst is prepared by dissolving 0.83 g of ammonium
metatungstate in 100 mL of distilled water, stirring the resulting
solution with 5 g of silica gel (300 m.sup.2/g, pore volume 1
mL/g), evaporating the water, then calcining the resulting solid in
air at 550.degree. C. for 6 hours. The resulting supported tungsten
oxide catalyst is then mixed with hydrotalcite at a weight ratio of
about 1:5 tungsten oxide catalyst/hydrotalcite. A metathesis
reactor is then prepared by adding the tungsten oxide
catalyst/hydrotalcite catalyst to a fixed-bed tubular reactor.
An ethylene guard column is prepared by loading a fixed-bed tubular
reactor sequentially with approximately equal amounts of
hydrotalcite and .gamma.-alumina, and a butene guard column is
prepared by loading a fixed-bed tubular reactor sequentially with
the tungsten oxide catalyst (prepared as described above) and
approximately twice the amount (by weight) of hydrotalcite.
The disproportionation reaction is carried out by first purging the
guard columns and metathesis reactor with an approximately 100
mL/min flow of N2 at atmospheric pressure. The purged reactor and
guard columns are then heated to 500.degree. C. with continuing N2
flow for 1 hr. The guard columns and reactors are maintained at
500.degree. C.; then approximately 100 mL/min of H2 gas at
atmospheric pressure is added to the N2 purge, and maintained for 2
hrs. The reactor is then cooled to 200.degree. C., and the guard
columns cooled to 50.degree. C., and the flow of N2 and 112 is
reduced to 50 mL/min. After purification in the respective guard
columns, liquefied renewable 2-butene is then introduced into the
butene guard column at a rate of 0.10 g/min, and liquefied
renewable ethylene is introduced into the ethylene guard column at
a flow rate of 64.5 mL/min and a pressure of 3.5 MPa. The ethylene,
2-butene, and H2 (7.0 mL/min, 3.5 MPa) were then charged into the
metathesis reactor (after preheating to 200.degree. C.). The butene
conversion rate obtained by subtracting the total amount of
trans-2-butene, cis-2-butene and 1-butene contained in the outlet
gas from the metathesis reactor is 71%. The propylene selectivity
based on butene is 90%. Small amounts of propane, pentene and
hexene are also produced.
Example 11
Oligomerization of Isobutene
The product stream from Example 4a was dried over molecular sieves,
compressed to 60 psig, cooled to 20.degree. C. so that the
isobutene was condensed to a liquid and pumped with a positive
displacement pump into a fixed-bed oligomerization reactor packed
with a commercial ZSM-5 catalyst (CBV 2314). The reactor was
maintained at 175.degree. C. and a pressure of 750 psig. The WHSV
of the isobutene-rich stream was 15 hr.sup.-1. The reactor effluent
stream was 10% unreacted butenes, 60% isooctenes (primarily
2,4,4-trimethylpentenes), 28% trimers, and 2% tetramers.
Example 12
Oligomerization of Isobutene
The product stream from Example 4a is co-fed with 50% isobutane to
a compressor, condensed and pumped into a fixed-bed oligomerization
reactor packed with Amberlyst 35 (strongly acidic ionic exchange
resin available from Rohm & Haas). The reactor is maintained at
120.degree. C. and a pressure of 500 psig. The WHSV of the
isobutene-rich stream is 100 hr.sup.-1. The product stream is about
50% isobutane (diluents), about 3% unreacted butenes, about 44%
isooctenes (primarily 2,4,4-trimethylpentenes), and about 3%
trimers.
Example 13
Dehydrocyclization of Isooctene
Isooctene from Example 11 was distilled to remove trimers and
tetramers and then fed at a molar ratio of 1.3:1 mol nitrogen
diluent gas to a fixed bed reactor containing a commercial chromium
oxide doped alumina catalyst (BASF D-1145E 1/8''). The reaction was
carried out at atmospheric pressure and a temperature of
550.degree. C., with a WHSV of 1.1 hr.sup.-1. The reactor product
was condensed and analyzed by GC-MS. Of the xylene fraction,
p-xylene was produced in greater than 80% selectivity. Analysis by
method ASTM D6866-08 showed p-xylene to contain 96% biobased
material.
Example 14
Hydrogenation of Isooctene
Palladium on carbon (0.5% Pd/C, 2 g) catalyst was charged into a
2000 mL stainless steel batch reactor equipped with stirrer. 1000
mL of a hydrocarbon fraction comprising isooctene isomers was
charged into the reactor. The reactor was then flushed with
nitrogen and pressurized with 100 psig hydrogen. The reaction
mixture was stirred for one hour and the temperature was increased
from ambient temperature to 80-100.degree. C. The reactor was
subsequently cooled down to ambient temperature and excess hydrogen
remaining in the reactor was released, and the reactor purged with
a small amount of nitrogen. The product was filtered off from the
catalyst and GC analysis of the product showed 100%
hydrogenation.
Example 15
Oxidation of Renewable P-Xylene to Terephthalic Acid
A 300 mL Pan reactor was charged with glacial acetic acid,
bromoacetic acid, cobalt acetate tetrahydrate, and p-xylene,
obtained from Example 13, in a 1:0.01:0.025:0.03 mol ratio of
glacial acetic acid:bromoacetic acid: cobalt acetate tetrahydrate:
p-xylene. The reactor was equipped with a thermocouple, mechanical
stirrer, oxygen inlet, condenser, pressure gauge, and pressure
relief valve. The reactor was sealed and heated to 150.degree. C.
The contents were stirred and oxygen was bubbled through the
solution. A Pressure of 50-60 psi was maintained in the system and
these reaction conditions were maintained for 4 h. After 4 h, the
reactor was cooled to room temperature. Terephthalic acid was
filtered from solution and washed with fresh glacial acetic
acid.
Example 16
Purification of Renewable Terephthalic Acid
Terephthalic acid from Example 15 was charged to a 300 mL Pan
reactor with 10% Pd on carbon catalyst in a 4.5:1 mol ratio of
terephthalic acid:10% Pd on carbon. Deionized water was charged to
the reactor to make a slurry containing 13.5 wt. % terephthalic
acid. The reactor was equipped with a thermocouple, mechanical
stirrer, nitrogen inlet, hydrogen inlet, pressure gauge, and
pressure relief valve. The Parr reactor was sealed and flushed with
nitrogen. The Parr reactor was then filled with hydrogen until the
pressure inside the reactor reached 600 psi. The reactor was heated
to 285.degree. C. and the pressure inside the vessel reached 1000
psi. The contents were stirred under these conditions for 6 h.
After 6 h, contents were cooled to room temperature and filtered.
The residue was transferred to a vial and N,N-dimethylacetamide was
added to the vial in a 5:1 mol ratio of
N,N-dimethylacetamide:terephthalic acid. The vial was warmed to
80.degree. C. for 30 minutes to dissolve the terephthalic acid. The
contents were filtered immediately; Pd on carbon was effectively
removed from the terephthalic acid. Crystallized terephthalic acid
filtrate was removed from the collection flask and was transferred
to a clean filter where it was washed with fresh
N,N-dimethylacetamide and dried. A yield of 60% purified
terephthalic acid was obtained.
Example 17
Polymerization of Terephthalic Acid to Make Renewable Pet
Purified terephthalic acid (PTA) obtained from Example 16 and
ethylene glycol are charged to a 300 mL Parr reactor in a 1:0.9 mol
ratio of PTA:ethylene glycol. Antimony (III) oxide is charged to
the reactor in a 1:0.00015 mol ratio of PTA:antimony (III) oxide.
The reactor is equipped with a thermocouple, mechanical stirrer,
nitrogen inlet, vacuum inlet, condenser, pressure gauge, and
pressure relief valve. The Parr reactor is sealed, flushed with
nitrogen, heated to a temperature of 240.degree. C., and
pressurized to 4.5 bar with nitrogen. Contents are stirred under
these conditions for 3 h. After 3 h, the temperature is increased
to 280.degree. C. and the system pressure is reduced to 20-30 mm by
connecting the reactor to a vacuum pump. Contents are stirred under
these conditions for 3 h. After 3 h, the vacuum valve is closed and
the contents of the reactor are flushed with nitrogen. The reactor
is opened and contents are immediately poured into cold water to
form PET pellets.
Example 18
Preparation of Diisobutylene from Isobutanol
Isobutanol produced by fermentation was separated from the
fermentation broth by distillation. The isobutanol, which contains
16% water, was passed through a chemical reactor containing a
commercial .gamma.-alumina catalyst heated to 310.degree. C. at
.about.10 psig and a WHSV of 6 hr.sup.-1. The water drained from
the bottom of the reactor contained less than 0.1 M isobutanol, and
isobutylene (gas) was collected with >99% conversion. The
isobutylene gas was dried by passing it through molecular sieves,
and was then fed into a second reactor containing a ZSM-5 catalyst
maintained at 140-160.degree. C., ambient pressure, and WHSV=1.5
hr.sup.-1 to give .about.60% conversion to a mixture of about 80%
of diisobutylene isomers and about 20% triisobutylene isomers and
minor quantities of higher molecular weight products.
Example 19
Preparation of Isododecane from Isobutanol
Isobutanol produced by fermentation (e.g. according to Example 1)
was separated from the fermentation broth by distillation. The
isobutanol, which contains 16% water, was passed through a chemical
reactor containing acidic commercial .gamma.-alumina catalyst
heated to 310.degree. C. at .about.10 psig and a WHSV of 6
hr.sup.-1. The water drained from the bottom of the reactor
contained less than 0.1 M isobutanol, and isobutylene (gas) was
collected with >99% conversion. The isobutylene gas was dried by
passing it through molecular sieves, and was then fed into a second
reactor containing Amberlyst.RTM. 35, maintained at 100-120.degree.
C., ambient pressure, and WHSV=2.5 hr.sup.-1 to give .about.90%
conversion to a mixture of about 15% of diisobutylene isomers, 75%
triisobutylene isomers and 10% tetramers. The liquid product was
pumped to a trickle-bed hydrogenation reactor packed with a
commercial 0.5% Pd on alumina catalyst and co-fed with 10% excess
hydrogen. Hydrogenation of >99% of the olefins occurred at
150.degree. C., 150 psig, and WHSV=3 hr.sup.-1. The saturated
hydrocarbon product was collected with an overall process yield of
.about.90%.
Example 20
Preparation of Gasoline from Dimers and Trimers of Isobutylene
A mixture of about 80% diisobutylene isomers and about 20%
triisobutylene isomers and minor quantities of higher molecular
weight products was fed into a hydrogenation reactor containing a
0.5% Pd on alumina catalyst maintained at 150.degree. C. and 150
psi to give a saturated hydrocarbon product, which was distilled at
atmospheric pressure to give three fractions containing
diisobutylene, triisobutylene and small quantities of higher
molecular weight products. The three fractions can be separated and
used in aviation gasoline and auto gasoline.
Example 21
Preparation of Methylundecene from Isobutylene
90 g of renewable isobutylene was loaded into a 350 mL batch
reactor with 10 g of a ZSM-5 catalyst (Si:Al ratio=80) that had
been treated with 2,4,6-trimethyl pyridine. The sealed reactor was
heated to 220.degree. C. and allowed to react for approximately 40
hours. 75 mL of product was collected and a sample was analyzed by
GC/MS. The composition was approximately 30% C.sub.12 or larger
molecules and the primary compounds were isomers of
methylundecene.
Example 22
Preparation of Diesel Fuel from Methylundecene
The unsaturated product from Example 21 was loaded into a 350 mL
batch reactor containing 1 g of 5% Pd/C catalyst. The reactor was
flushed with nitrogen and pressurized with 200 psig of hydrogen.
The reactor was heated to 100.degree. C. and held at this
temperature for 1 hour. 70 mL of product was collected and analyzed
by GC/MS. The product was found to be fully saturated. 70 mL of
this hydrogenated mixture was then distilled to concentrate the
C.sub.12+ fraction (e.g., the fraction containing C.sub.12 or
higher hydrocarbons). Approximately 50 mL of the mixture was
distilled off (primarily C.sub.8 hydrocarbons), leaving 20 mL of
C.sub.12+ hydrocarbons. The flash point of the final product was
measured as 51.degree. C. and the derived cetane number was
measured by ASTM D6890-07 as 68. The product was determined to meet
the ASTM specifications for #1 diesel fuel.
Example 23
Jet Fuel from Isobutylene
Renewable isobutylene was trimerized using a fixed bed continuous
flow system equipped with a tube furnace housing SS 316 reactor (OD
5/16 in.times.12 in), gas flow meters, an HPLC pump, a back
pressure regulator, and a gas-liquid separator. In a typical
trimerization procedure, the reactor was loaded with .beta. Zeolite
CP 814C (Zeolyst International) and isobutylene was fed at WHSV 1-3
hr.sup.-1 at a reaction temperature of 140-180.degree. C., at
atmospheric pressure. The isobutylene conversion was 85% with a
product distribution of about 29% dimer isomers, 58% trimer
isomers, and 11% tetramer isomers. The hydrogenation of the
resulting oligomer blend was carried out at 150.degree. C. and 150
psi H.sub.2 to give a hydrocarbon product which was fractionated to
provide a blend of saturated C.sub.12 (trimers) and C.sub.16,
(tetramers) hydrocarbons that were used as a jet fuel
feedstock.
Example 24
Preparation of BTEX from Isobutylene
A fixed bed continuous flow system equipped with a tube furnace
housing SS 316 reactor (OD 5/16 in.times.12 in), gas flow meters,
an HPLC pump, back pressure regulator, and a gas-liquid separator
was loaded with ZSM-5 CBV 8014 Zeolite catalyst. The catalyst was
calcined at 540.degree. C. under N.sub.2 for 8 hrs before the
reaction was started. Isobutylene (e.g., prepared as described
herein) was fed into the reactor at WHSV 1.0 hr.sup.-1 and the
reaction conditions were maintained at 400-550.degree. C. and
atmospheric pressure. Aromatic products were formed in about 45%
yield and the selectivity for BTEX (e.g., benzene, toluene,
ethylbenzene and xylene) was 80%. The aromatic product was
separated and used in fuels and other products.
Example 25
Preparation of BTEX and Hydrogen from Diisobutylene
A fixed bed continuous flow reactor was loaded with ZSM-5 CBV 8014
Zeolite catalyst. Prior to initiating the reaction, the catalyst
was calcined at 540.degree. C. under N.sub.2 for 8 hrs. Isobutylene
was fed into the reactor at a WHSV of 1.6 h.sup.-1 while the
reaction conditions were maintained at 400-550.degree. C. and
atmospheric pressure. Aromatic products were formed in about 38%
yield and with a selectivity for BTEX of 80%. The aromatic products
were isolated and used in fuels and other products. Hydrogen also
was produced as a byproduct of the reaction; about 3 moles of
hydrogen were produced for each mole of aromatic ring formed.
Example 26
Integrated Oligomers Production from Isobutylene
Isobutanol produced by fermentation (e.g., as described herein) was
separated from the fermentation broth by distillation. The
isobutanol, which contains 16% water, was passed through a chemical
reactor containing pelleted SPA catalyst heated to 350.degree. C.
at 1 atmosphere. Water was drained from the bottom of the reactor
and isobutylene was collected with 99% conversion. The isobutylene
gas was dried by passing it through molecular sieves, and was then
fed into a second reactor containing Amberlyst.RTM. 35 (Rohm and
Haas) catalyst maintained at 120-140.degree. C. and ambient
pressure to give 90% conversion to a mixture of about 27% of
diisobutylene isomers and about 70% triisobutylene isomers, and
minor quantities of higher molecular weight products.
Example 27
Integrated Saturated Oligomers Production from Isobutylene
Isobutanol produced by fermentation (e.g., as described herein) was
separated from the fermentation broth by distillation. The
isobutanol, which contains 16% water, was passed through a chemical
reactor containing pelleted SPA catalyst heated to 350.degree. C.
at 1 atmosphere. Water was drained from the bottom of the reactor
and isobutylene was collected with 99% conversion. The isobutylene
gas was dried by passing it through molecular sieves, and then fed
into a second reactor containing Amberlyst.RTM. 35 (Rohm and Haas)
catalyst maintained at 120-140.degree. C. and ambient pressure to
give 90% conversion to a mixture of about 27% of diisobutylene
isomers and about 70% triisobutylene isomers and minor quantities
of higher molecular weight products. This oligomers blend was then
fed into a third reactor to hydrogenate the olefins over 0.5% Pd
supported in alumina at 150.degree. C. and 150 psi H.sub.2. The
resulting product was fractionated to isolate a blend of
isobutylene trimers and tetramers that were used as a jet fuel
feedstock.
Example 28
Integrated Production of P-Xylene from Isobutanol
Renewable isobutanol is converted to renewable p-xylene using a
process illustrated in FIG. 10. Renewable isobutanol (e.g., as
described herein) is fed wet (15 wt % water) through a preheater
into a fixed-bed catalyst reactor packed with a commercial
y-alumina catalyst (BASF AL-3996) at a WHSV of 10 hr.sup.-1. The
dehydration reactor is maintained at 290.degree. C. at a pressure
of 60 psig. The effluent (3) from the dehydration reactor is fed to
a liquid/liquid separator, where water is removed. Analysis of the
organic phase (4) shows that it is 95% isobutylene, 3% linear
butenes, and 2% unreacted isobutanol. The organic phase is combined
with a recycle stream (11) containing isobutane, isooctane, and
unreacted butenes and fed to a positive displacement pump (P2)
where it is pumped to an oligomerization reactor packed with HZSM-5
catalyst (CBV 2314) at a WHSV of 100 hr.sup.-1. The reactor is
maintained at 170.degree. C. at a pressure of 750 psig. The
effluent (6) from the oligomerization reactor is analyzed and shown
to contain 60% unreacted feed (isobutane, isooctane, and butenes),
39% isooctene, and 1% trimers. The effluent from the
oligomerization reactor is combined with recycled isooctene (15)
and fed through a preheater and to a fixed bed reactor containing a
commercial chromium oxide doped alumina catalyst (BASF D-1145E
1/8'') at a WHSV of 1 hr.sup.-1. The dehydrocyclization reactor is
maintained at 550.degree. C. and 5 psia. The yield of xylenes from
the reactor relative to C.sub.8 alkenes in the feed is 42% with a
selectivity to p-xylene of 90%. The effluent (8) is separated with
a gas-liquid separator. The gas-phase is compressed (C1) to 60 psig
causing the isobutane and butenes to condense. A second gas-liquid
separator is used to recover the hydrogen (and small quantities of
methane or other light hydrocarbons). The C.sub.4 liquids are
recycled (11) and combined with the organic phase from the
dehydration reactor (4). The liquid product (12) from the
dehydrocyclization reactor is fed to a series of distillation
columns slightly above atmospheric pressure by a pump (P3). Any
by-product light aromatics (benzene and toluene) and heavy
compounds (C.sub.9+ aromatics or isoolefins) are removed. A side
stream (14) rich in xylenes and iso-C.sub.8 compounds are fed to a
second distillation column. The C8 compounds (isooctene and
isooctane) are recycled (15) to the feed of the dehydrocyclization
reactor. The xylene fraction (16) is fed to a purification process
resulting in a 99.99% pure p-xylene product and a small byproduct
stream rich in o-xylene.
The embodiments described herein and illustrated by the foregoing
examples should be understood to be illustrative of the present
invention, and should not be construed as limiting. On the
contrary, the present disclosure embraces alternatives and
equivalents thereof, as embodied by the appended claims.
* * * * *